Yesterday I successfully flashed three out of four S20 v2.1.0 devices with ESPHome firmware. While flashing the fourth one, I accidently interrupted one of the cables (most likely the power supply [3.3 V via TTL to USB adapter]) and since this the device is not recognized by the flashing tool (ESPHome Flasher) anymore. Is there a possibilty to fix this and to flash a firmware onto the device? Could this even be the problem? How could I check what the problem is?
Oh no. Sorry this happened ! I would try to erase the flash and format the file system and then try flashing it again.
See: (gotchas and the upgrading firmware pieces) https://nodemcu.readthedocs.io/en/latest/flash/