Flash firmware on ZBM-MG21 / MG24

Factory firmware is usually enough for ZHA. Use the official flasher if you need a different stack, a newer EZSP, or the stick is not recognized.

1. Open Inswift Silabs Flasher on this site
2. Download the Windows flasher and the .gbl firmware that matches the model and protocol
3. Connect over USB, close ZHA / Zigbee2MQTT, then select the serial port
4. Select the correct chip (MG21 or MG24); do not mix images
5. The LED may blink blue while flashing; unplug and replug before returning to HA

Stop anything using the serial port first so flashing can finish.