Two more data points. This time I had two 0.7.0 units in the field powered by a 12V 144AHr SLA, going through a Murata OKI-T/3-W32P-C DC/DC converter (4.5V output).
The battery deeply discharged after several days (resting voltage right now is 8.8V), and when I recovered the two Electrons one had a corrupted key[*] and the other shows the same dim D7. The incoming data shows that the device which stopped transmitting first was the one with the corrupted key, whereas the one with the (hopefully just) corrupted bootloader ran an extra 32 minutes.
The corrupted key was solved by using particle CLI’s key doctor. I haven’t gotten out my J-Link yet to see about reflashing the bootloader, so I don’t know for sure that it will come back to life.
So over a set of about 15 Electrons, I have now seen three corrupted keys and two dim D7 instances. I hadn’t linked the lost keys to the low power event till now, but it seems to me likely that the prior two key corruptions were because I ran the LiPo battery low and not because of some mishandling on my part.
Suggestions? I’m loving Particle and the Electron, but 5 failures which require sending the devices back to me for reflashing/re-keying isn’t something we can live with.
[*] I’m calling it corrupted because the device is unable to get back online until I reset the key certificate. Then everything works normally.