Step

1. First, you need to update the ESP32's built-in firmware, open the `UpdateFirmware` example, compile and burn it into the board.

2. Unzip `SIM800_Series_download_Tools_Customer_v1.23.rar`

3. Open `Flash_tool.exe`

4. Select the relative firmware and port according to the diagram

5. Wait for the board indicator to light up, then click the `Start Download` button, and wait for it to finish

Firmware Link