My V1.3.1-rc1 Boron (B40HAB9139CRJ8X) was faithfully uploading telemetry data until 1pm today.
I have recovered the remote unit to discover the unit is totally broken and will not turn on when plugged into USB. It was found dead with LED off.
When one plugs this dead Boron into regulated 5V USB, the LED will become solid white for less than a second and then totally die - shut off as if it failed to boot or something.
However, with a LiPo connected, it will now magically turn on and connect. This is very frustrating as the Boron was failing to charge the LiPo during deployment, and the battery was 0% when it died at 1pm today (the whole time, Boron has been powered with regulated 5V on the USB pin).
-Boron deployed about a month ago
-+5V to USB pin using L7805 regulator from 6V SLA battery, solar powered
-LiPo has been connected throughout the deployment
-LiPo charge fell gradually until hovering between 2 and 5 percent in the last few days, finally recently to hit zero
-Particle console showed USB charge symbol intermittently, however LiPo never fully charged
-5V to GND inputs had 0.1uf bypass capacitor
-My charge code executed on setup was:
-I want to use Particle for my projects, but I need to have reliability. I know it is possible because I have another Boron unit not having this issue (it however has a 12v solar system).
Can someone very knowledgeable about the Boron hardware and power supply/regulator comment on the clear hardware power-related failures I’m experiencing with Boron and what can be done to mitigate them for 100% reliability?
Update: The unit will connect to cloud on USB-power-only when I hold down Mode and Reset to enter safe mode (purple flashing). Currently investigating hypothesis that the setup call to PMIC code above is causing a software-related crash, which would mean this is not a hardware issue. Indeed I did seem one time a few weeks ago to observe legal PMIC calls totally crashing a Boron to a dead-seeming state.