Step 1: Shortcut GPIO00+GND, connect device via serial cable, remove shortcut bridge

./esptool/esptool.py --port /dev/ttyUSB0 --baud 115200 erase_flash

Step 2: Remove device, shortcut GPIO00+GND again, connect device via serial cable, remove shortcut bridge.

./esptool/esptool.py --port /dev/ttyUSB0 --baud 115200 write_flash --flash_mode dout 0x0 tasmota-1m-de.bin