Steady Blue LED but no boot (was in shock but recovered)

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User avatar
ccs_hello
Posts: 440
Joined: Sat Oct 13, 2018 9:16 pm

Wed Feb 20, 2019 2:29 am

TL;DR
Lengthy sequence of events for the curious. Jump to the next post to see the abbreviated version...

The other night when I was playing the USB-C port "change over from power sink mode into power source mode" feature, my LPA 864's Win10-Pro crashed and went into reboot.
LPA did not come back up. No screen displayed on my HDMI monitor but Blue LED was steady on, my USB keyboard's Num_lock light did not lit. At that time I was using 12V DC feed which has a power meter hookup. Current draw was a stable 400mA (or 200mA sorry I forgot). CPU fan did not have the usual quick 0.5 second spin up cycle.
OMG, the LPA 864 seems to be live (since Blue LED was on all the time), but seems to be out of reach
At this non-activity state, most of us will call this SBC was dead. (No it was not, because I see it is drawing 400 mA from my 12V power supply.

Use the "remove RTC battery" suggestion, I took out that tiny CR927 Lithium battery carefully and let the LPA unpowered in that state for overnight.
Checked that RTC battery voltage, it was a low 2.7V.

Next day, I checked the battery voltage again, it recovered a little bit to 2.9V. By experience, I knew this battery probably is in its last mile anyway. Decided not to reuse it/put it back in. Turned out to be it's a good move.

Without the RTC battery, I plugged in the DC12V power, monitored the power meter and the Blue LED. This time, the SBC will reboot itself twice by itself.
That is: when power was first applied, the Blue LED slowly blinking at approx ever 2 seconds. Press and hold the "power" button to get it into steady Blue state. I can see the DC power consumption going up and varied a bit, stayed in that state for no more than 10 seconds. Then LPA will reboot ( < -- this was the first reboot) by itself (saw power consumption dropped down to a very low level) then DC power consumption going up and varied a bit, stayed in that state for no more than 10 seconds. Then LPA will reboot by itself (this is the second reboot.) The third time, the screen showed up and my keyboard's Num-Lock light came up as well. Wow! the LPA saved itself!

What I think that was happening... (please read my next post)

User avatar
ccs_hello
Posts: 440
Joined: Sat Oct 13, 2018 9:16 pm

Wed Feb 20, 2019 2:44 am

It seems that the BIOS settings may have three different states: corrupted state, virgin state, and initialize-n-fully-operational state.

I am guessing when my LPA864 was "gone fishing", the BIOS settings might have been corrupted for some reasons (see next post on my own guessing/root cause analysis),
this was the "shock" (heart sank) I initially felt (have a strong heart, no panicking yet...)

By the fact that I removed the RTC battery (and not inserting the weak battery back in), wait for awhile, I think the BIOS settings are being considered as "virgin"/un-initialized state.

My LPA864, after the power on, (sensed that BIOS settings is uninitiated) will perform its own auto-recovery routine. In my case, rebooted itself twice to get the settings good enough to be "come alive".

--- side note ---
At this point, since there is no RTC battery in place, if I unplug the DC power feed, the BIOS will go back to the "virgin" state.
Next time, when I reapply the DC power, the same reboot twice event will happen again.
(BTW, in my experience, I do not need to wait for too long for this DC power removal-then-replug sequence. 2 to 3 minutes is definitely long enough. No need for several hours and definitely not overnight.)
Key is to take out the RTC battery and do not put it back such that LPA864 will do its BIOS setting re-initialization thingie.

User avatar
ccs_hello
Posts: 440
Joined: Sat Oct 13, 2018 9:16 pm

Wed Feb 20, 2019 3:06 am

For the curious, CR927 battery has its own thread: https://www.lattepanda.com/topic-f23t18497.html

Reiterate: do not put the weak battery back in, since it may not trigger the BIOS setting "reinitialization" activities.

Possible root causes I think might be these:
- too weak the battery (becomes flaky)
- USB-C port change over from PD sink mode to PD source mode
- power surge of some sort

Adding several pictures:
IMG_0045.jpg
IMG_0045.jpg (70.73 KiB) Viewed 5281 times
DC power meter

---------------------

Use a larger CR2032 Lithium battery for RTC battery:
IMG_0042.jpg
IMG_0042.jpg (39.59 KiB) Viewed 5281 times
IMG_0043.jpg
IMG_0043.jpg (34.61 KiB) Viewed 5281 times
IMG_0044.jpg
IMG_0044.jpg (138.19 KiB) Viewed 5281 times

User avatar
jherrick
Posts: 4
Joined: Thu Feb 14, 2019 5:08 am

Thu Feb 21, 2019 10:27 pm

Seems to be two major issues with these boards, one where the LPA led lights up but not in the correct sequence. This one seems to be fixable by using the RTC method or using a 12v external power source through the DC connector.

The second is where the LEDs dont light up at all, these units seem to be completely dead with no quick fix. Im curious if the users of these units are leaving their pandas running, not just "playing" with them for 2-3 hours a couple days in the week. In my case they were running 24/7 with Windows 10 Pro balanced power plan in stock mode (i.e. no turbo adjustments set).

User avatar
fruvous
Posts: 6
Joined: Fri Sep 02, 2016 9:01 pm

Thu Mar 28, 2019 9:57 pm

jherrick wrote:
Thu Feb 21, 2019 10:27 pm
The second is where the LEDs dont light up at all, these units seem to be completely dead with no quick fix. Im curious if the users of these units are leaving their pandas running, not just "playing" with them for 2-3 hours a couple days in the week. In my case they were running 24/7 with Windows 10 Pro balanced power plan in stock mode (i.e. no turbo adjustments set).
My second LP Alpha died yesterday and had left it on 24/7.

User avatar
THW Mark
Posts: 11
Joined: Tue Jan 08, 2019 2:55 pm

Mon Apr 01, 2019 1:46 pm

ccs_hello wrote:
Wed Feb 20, 2019 2:29 am
Without the RTC battery, I plugged in the DC12V power, monitored the power meter and the Blue LED. This time, the SBC will reboot itself twice by itself.
That is: when power was first applied, the Blue LED slowly blinking at approx ever 2 seconds. Press and hold the "power" button to get it into steady Blue state. I can see the DC power consumption going up and varied a bit, stayed in that state for no more than 10 seconds. Then LPA will reboot ( < -- this was the first reboot) by itself (saw power consumption dropped down to a very low level) then DC power consumption going up and varied a bit, stayed in that state for no more than 10 seconds. Then LPA will reboot by itself (this is the second reboot.) The third time, the screen showed up and my keyboard's Num-Lock light came up as well. Wow! the LPA saved itself!
Interesting findings and thanks much for sharing. As I posted in another thread, i seem to have had a similar issue. After using my panda every other day (shut down at night) for a couple of weeks, one day it shut down itself and did not get back on. when i power it, the blue light keeps on flashing every 2-3 seconds like you describe.

Are you suggesting it is in corrupted state and would benefit from removing the RTC battery?

User avatar
ccs_hello
Posts: 440
Joined: Sat Oct 13, 2018 9:16 pm

Mon Apr 01, 2019 1:58 pm

Press-n-hold the power button for few seconds. Does it turn to solid BLUE (means LPA is now powered on)? < -- you may not see screen or other activities at this time, just solid BLUE

If that's the case, try removing RTC battery trick.

User avatar
THW Mark
Posts: 11
Joined: Tue Jan 08, 2019 2:55 pm

Tue Apr 02, 2019 8:20 pm

ccs_hello wrote:
Mon Apr 01, 2019 1:58 pm
Press-n-hold the power button for few seconds. Does it turn to solid BLUE (means LPA is now powered on)? < -- you may not see screen or other activities at this time, just solid BLUE

If that's the case, try removing RTC battery trick.
pity. seems to be a different problem. when i plugin the supplied usb-c pd adapter, the blue light just starts flashing every few seconds, that is it. doesn't respond to poweron. tried removing the rtc battery (no options left anyway) but that doesn't seem to do a whole lot.

next thing to try is direct 12v power.... :(

User avatar
ccs_hello
Posts: 440
Joined: Sat Oct 13, 2018 9:16 pm

Tue Apr 02, 2019 10:11 pm

Please use a small flat-blade screwdriver to short the two pins on the "SW" connector socket for few seconds (which is also the "Power Switch")
to verify it is not the power push button that is in trouble.
(Be careful on using any metalic object near the motherboard.)

P.S. I use my DIY power switch nowadays. Much easier than that tiny push button switch.
LPA_sw.jpg
LPA_sw.jpg (149.02 KiB) Viewed 4639 times

User avatar
NotThatGuyAgain
Posts: 2
Joined: Wed Mar 27, 2019 8:55 am

Fri Jun 07, 2019 3:42 am

Hi All,

First of all I know this is a MEGA LONG post but I have apologized for such nearing the end ... I will do so here to start also.

Second ... I just want to say that @css_hello ... you Sir are a Gentleman and a scholar and should be commended for your efforts around this forum ... you certainly seem to know your stuff well and are very active in trying to assist others in posting your findings and thoughts.

I am saying this because I was just about ready to throw this LattePanda Alpha 864 (Win 10 Pro Activated) in the garbage bin this very morning (or at least check my date of purchase and ask for a full refund from DFRobot or go through an RMA effort) after having changed some BIOS settings and then getting the solid blue light with no display issue ... may I also say that after having the 864 for only a few days I discovered the issue of the default PSU not working and rigged up my own DC power supply which in a way was very satisfying after getting the thing working again but at the same time I really wanted that default PSU to work as I wanted the nice LP branding on display at my home office desk ... aesthetics aside for now ...

Here is what happened in my case:
  • Connected a freshly formatted Samsung EVO 850 500GB M.2 SSD (all unallocated space after formatting in my primary machine) into the M.2 key M slot in the Panda
  • Booted Win 10 Activated (obviously via the onboard EMMC) and created a new Simple Volume for the SSD (single partition) via Disk Management whilst assigning a drive letter
All good so far and this was with the intention of, and in preparation for creating a Triple boot system (Windows/Linux/Mac OS) following the guide as advised by Novaspirit Tech RE: YouTube.

That being the case, I changed the following settings in BIOS as advised by one his videos:
  • Advanced -> CPU Configuration -> VT-d -> Set to Disabled
  • Chipset -> Wake System from S5 -> Set to Disabled
  • Chipset -> Graphics Configuration -> Primary Display -> Set to IGFX
  • Chipset -> Graphics Configuration -> Aperture Size -> Changed from 256MB to 1024MB
  • Security -> Secure Boot -> Set to Disabled
  • F4 Save and Exit -> YES
At this point the LP rebooted and I was back into Windows without a problem, however, in the interest of testing and without trying to rush in and stick in my USB flash drive formatted with Mac OS and with Clover at the ready, I decided to ...
  • Reboot and enter BIOS
  • Reverse all settings I had changed back to the original settings prior to change including re-enabling of Secure Boot
IMPORTANT NOTE (I feel anyway): on the re-enabling of the Secure Boot option there was a message about a key of some sort ... unfortunately I did not take note of the exact output but I will say that it made me somewhat concerned upon reading it but I seemed to have no other option but to continue on that path with the message possibly informing me that a Reset or Reboot would be required ... not exactly sure (if anyone knows what this message was and if there is a solution to it/option I should have taken then please explain)?

So anyways ... I saved and exited and upon the reboot ... SOLID BLUE PWR LIGHT BUT NO DISPLAY (I.e., on my HDMI connected 40" HiSense TV which I use as my primary monitor it did nothing but indicate No Signal) ... OH OHHHHHH!!!

At this point panic definitely set in, however I can now say that I am very happily typing out this post via the LP after:
  • First removing the SSD and leaving it disconnected throughout the following
  • Several attempts to boot normally (I.e., using the small default power on button) = NO SUCCESS
  • Disconnecting the Ethernet/HDMI/Wireless KB&Mouse Dongle/PSU -> Turning the display off -> Reconnecting all above listed to the LP -> Power on display -> attempt to boot normally = NO SUCCESS
  • Remove RTC and noted the triple reboot sequence happening via the blue PWR LED -> did this several times without any keyboard input but at this stage it was just a repetitive cycle of disconnect everything then reconnect and attempt to boot normally with the same end result = NO SUCCESS (I.e., solid blue PWR LED but no display)
  • In the interest of a test I shorted the SW pins but same end result
  • FINALLY SUCCESS: Removed Wireless KB/Mouse dongle and connected another keyboard (no LED indicators on the KB I used) via USB -> Removed the RTC battery -> tried booting normally noting the triple reboot sequence but still final result of solid blue PWR LED with no display -> whilst still powered (solid blue PWR LED) yanked the DC power supply from the wall socket -> waited about 5 minutes and reconnected DC power whislt mashing the ESC key the whole time it rebooted ... I believe that it still went through another triple boot sequence but I just kept hammering away at the ESC key the whole time and then did the F3 Enter F4 Enter to blindly reset optimal BIOS settings as mentioned in other threads -> at this point I think a little bit of patience was the key because at first it was still unresponsive (I.e., it seemed to take say at least 30 seconds ... if not a minute or two for the display to pop back up and I was in action ... HOORAY!!!
I guess I'm going to have to do some more investigating and not blindly following tutorials which tell me to change settings in BIOS without fully understanding what the consequences could be ... either that or I just scrap the idea of a triple boot but I really would like to try out Mac OS even though I'm more a fan of Windows and more so of Linux and even though a lot of people say that MAC is absolute garbage ... just that I've never had a MAC and with me getting in on the LP with the m3-7Y30 I thought why not give it a go.

So yeh anyways ... last of all ... apologies for the full length book like post as I said at the very beginning but I wanted to relay my experience in the hope that it might stop that heart breaking feeling of someone else when things don't go exactly as planned and as @css_hello has done try to post what I remember of the event and learned along the way.

Again @css_hello ... you are to be commended for your efforts within this community so a very, VERY big TY to you :)

Cheers from Glenn in Australia

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