Program your board using the esptool.py program, found here.
If you are putting MicroPython on your board for the first time then you should first erase the entire flash using:
esptool.py --chip esp32s2 --port /dev/ttyACM0 erase_flash
From then on program the firmware starting at address 0x1000:
esptool.py --chip esp32s2 --port /dev/ttyACM0 write_flash -z 0x1000 board-20210902-v1.17.bin