I am trying to get the Feather nRF52840 to be recognized by my computer as FTHR840BOOT. I had it connected at one point, and loaded the adafruit_circuitpython_etc.uf2 file, creating the CIRCUITPY drive. However, the device ejected itself as I was trying to load other files and I can’t get it connected to the computer again. I’ve tried double-pressing the reset button, which worked once, but the device is again non-responsive. Please advise.
At first, check if your USB cable is good and capable of data transfer. If yes, double-tap the reset button of the board quickly (within ~0.5 seconds). If successful, the FTHR840BOOT drive should appear.
If it works: Reflash the UF2 file again (adafruit_circuitpython_*.uf2) immediately.
If you cannot get the board to enter bootloader mode, you may need to reflash the bootloader using SWD (J-Link debugger) or follow Adafruit’s guidelines with a second nRF52-based board.
Adafruit has a detailed guide here:
Since you are using nRF52840, you can make an nRFMicro/Pro Micro compatible Bluetooth LE board.