Microwave shows E5 and will not start; sometimes accompanied by a humming noise and immediate shutdown.

Safety first: Unplug the microwave. Inverter-based microwaves use high-frequency high-voltage circuits that are dangerous to service without training.

• Reset attempt: Leave the microwave unplugged for at least 10 minutes to allow internal capacitors to discharge and the control board to reset. Plug back in and test.
• Check for obvious damage: Remove the outer cover and inspect the inverter board (usually a separate PCB near the magnetron) for burnt components, cracked solder joints, or blown fuses.
• Inspect magnetron: If the magnetron is shorted, it can cause the inverter to fail. Look for burn marks or a strong burnt odor around the magnetron.
• Replace inverter board: If there is visible damage or if the E5 code persists, the inverter board typically must be replaced as a complete assembly with an Ambiano-compatible inverter module.

Note: Inverter and magnetron diagnosis should be performed by a qualified technician due to shock risk.