Burn the bootloader with a Segger J-link

• Install the JLink Software and Documentation Pack from Segger.

Make sure the OHB is powered on.

In the Arduino IDE

• Select Tools > Board > Adafruit Bluefruit Feather52
• Select Tools > Programmer > J-Link for Feather52
• Select Tools > Burn Bootloader with the board and J-Link connected

Burn the bootloader from the command line with nrfjprog

• Install the nrf command line tools
• In a terminal, run

  nrfjprog --program <PATH_TO_ARDUINO>/packages/movuino/hardware/movuino/1.0.0/bootloader/feather_nrf52840_express/feather_nrf52840_express_bootloader-0.3.2_s140_6.1.1.hex -f nrf52 --chiperase --reset