micropython/ports/stm32/boards/ARDUINO_PORTENTA_H7/deploy.md

Via dfu-util

This board can programmed via DFU bootloader, using e.g. dfu-util. To enter the DFU bootloader, double tap the reset (blue) button, or you can use machine.bootloader() from the MicroPython REPL.

dfu-util -w -d 2341:035b -a 0 -d 0x8040000 -D firmware.dfu

Or from MicroPython source repository:

make BOARD=ARDUINO_PORTENTA_H7 deploy