micropython/ports/esp32/boards/ARDUINO_NANO_ESP32/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 -d 0x2341:0x0070 -R -D build-ARDUINO_NANO_ESP32/micropython.app-bin

Please note that the DFU bootloader comes factory flashed. Should you for any reason erase the entire flash, the DFU bootloader will have to be re-installed. Please follow the instructions here to do so.