Nerdonic Exen Mini (SAMD21/Trinket M0 clone) questions

I purchased a Nerdonic Exen Mini for a project, and it doesn’t appear to be well-documented. I was curious if anyone had any experience with this board or could shed some light on a few questions I had. It is programmed using the “Arduino/Genuino Zero” (Native USB port).

  1. Can the power LED be disabled (or software disabled via h/w modification)? As far as I can tell, it doesn’t honor “digitalWrite(LED_BUILTIN, LOW)” to disable the built-in power LED. The secondary blue LED can be changed by writing to Pin 8, but not the power LED.
  2. Can PA10/PA11 be used as the native port, or used to read/write USB data? The micro-USB connector is a bit large and I’d like to remove it.
  3. Is there some really reliable way of getting the device into bootloader mode w/out powering the device via external USB first? I was reading about native port problems and tried adding a delay() at the beginning of my setup, but that doesn’t seem to affect anything. Ultimately I have to power the board via external USB, put it into bootloader mode and then connect it to the PC. Otherwise, Windows complains (typical not-detected error). The Adafruit Trinket M0 doesn’t seem to have this issue.
  4. Can I upgrade the bootloader on this device using the IDE?

Any insight is greatly appreciated!