Trying to emulate a USB flash drive using Nano PI Duo2. Can anyone tell me how to use the button next to the USB port to run a command? Currently, it just shuts down the board.

I looked at the schematics. It seems the signal is AP-RESET, which is connected to GPIO L3. But what's the Linux GPIO number I can use ? Example:

echo 100 > /sys/class/gpio/export