NRF52840 Development Board Compatible With Nice!Nano V2.0 Bluetooth Split keyboard ProMicro NRF52840

The default factory built-in program is Blink-A11-IO (all IO ports automatically flip for 1 second), if you need to enter Nice! Please short-circuit RST to GND twice within 0.5 seconds for the Bootloader of NanoV2. Press the RST key twice on the keyboard board within 0.5 seconds