Dead Photon with Led D7 On

[ninjatill]

I think this is similar to other posts regarding the dim blue LED. It would require a JTAG programmer to reprogram the bootloader:

Spark core not responding. Only small blue LED is on

Unfortunately a Dim D7 is caused by an erased bootloader and can only be fixed by JTAG or SWD. It can’t even be fixed by USB. The lost keys, lost settings, and lost boot loader may be variations of this problem: When some situation, it tends to be a low-power brown-out type of situation, occurs, it appears that certain flash sectors can be erased. Sometimes, it’s the sector that contains settings (like Wi-Fi settings or device keys), and sometimes it’s the boot loader. When the boot loader ge…

Electron Wont boot up

Test pad D7 to GND. If the device is missing the bootloader D7 will be held high with a weak pull-up for JTAG/SWD. If you had a blue LED on D7 like the Electron, it would be on, dimly. If the problem is indeed the missing bootloader, then you’d need to flash that using SWD using a ST-LINK/v2 JTAG/SWD programmer (or similar). It needs to connect to D7, D6, 3V3, and GND.

St-link & programmer shield only! - So, you've decided you want to update your bootloader and everything

If we can get a clear way to reproduce the failure, then yeah, we would definitely want to debug.