Enter make

Stop the Klipper service.

sudo service klipper stop

Get the Duet's serial ID # and copy it down.

ls /dev/serial/by-id/*

Enter "make flash FLASH_DEVICE=" and paste your serial after the =

If the flash fails usually this will place the board into a bootloader mode like original install does when you hit the erase pins. If this occurs please rerun ls /dev/serial/by-id/* so that you can get the correct serial

Enter make "flash FLASH_DEVICE=" and paste your serial your new serial after the =