Xiaomi Mi Air Purifier 3H

Disassembly

The disassembly process is similar to Xiaomi Smart Air Purifier 4 Disassembly

Disassembly video for 3H model can be found here.

Pictures

The Board:

Flashing

• Power off the purifier
• Connect 3.3V, GND, TX and RX to your UART TTL adapter (no soldering needed if you use pin header)
• Short the two pins labeled GPIO0 and GND just above the UART pins to keep the ESP32 in bootloader mode (no soldering needed if you use pin header)
• Power on the board by connection the UART adapter to your computer (don't connect the main power of the purifier!)
• You should now be able to use your ESP flashing tool of choice, like esptool.py (which is already available in your ESPHome venv)
• Backup the full flash contents and put it somewhere safe
• Write the initial ESPHome build
• Power off the board by disconnecting the UART adapter from your computer
• Remove the GPIO0 and GND connection
• Power on the board by connection the UART adapter to your computer. You should now be able to observe ESPHome booting.

Process is similar to Xiaomi Smart Air Purifier 4 Lite Flashing. More information can also be found here.