If you are repairing a device, identifying the PCB revision is mandatory. V4 boards are physically distinguishable by three features:
The (Version 4) is a specific iteration of a custom motherboard PCB designed for the ESP32-C3 microcontroller. This board is commonly used in industrial and smart home automation projects, often featuring integrated LoRa communication and RS485 connectivity. Core Architecture & MCU c3e-mb-pcb-v4