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

userHead anonymous 2019-02-20 10:29:50 35694 Views9 Replies
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)