Photon not turning on and can't DFU after changing brownout level

Troubleshooting
3

Thanks for moving @jvanier .

I added this piece of code which gets called as the very last thing in my setup() function:

void Status::SetBrownOutResetLevel() {
  const uint8_t desiredBOR = OB_BOR_LEVEL3;
  if(FLASH_OB_GetBOR() != desiredBOR) {
    Serial.println("Writing BOR");

    FLASH_OB_Unlock();

    FLASH_WaitForLastOperation();

    FLASH_OB_BORConfig(desiredBOR);

    FLASH_OB_Launch();

    FLASH_OB_Lock();

    Serial.println("Done writing BOR");
  } else {
    Serial.println("BOR value already set");
  }
  Serial.println("");
}

I have LED’s attached to the device that show a ‘Start Up’ pattern - this is set early in setup().

First time I ran this code I started up, got the startup pattern on my LEDs and then next time I looked, there was no activity on the photon LED, it was blank.

I power cycled it and still nothing happens, the buttons on the device have no effect either. The little D7 LED is a dim blue colour.

Measuring 3.34V on the 3V3 pin.

I am running v0.5.1 system firmware.

I have a programmer shield v1.0.0 here - any quick reference to grabbing a memory dump?