Microwave shows E9 and will not start; interior light and display may still work.

Safety: Unplug the microwave before inspection. High voltage is present inside.

Basic checks:

• Listen for clicking sounds from the control board when pressing START. No click may indicate a failed relay or driver.
• Check that the interior light, fan, and turntable operate when expected. If one load is shorted, it may trigger E9.

Internal inspection (qualified DIYers/technicians):

• Remove the outer cabinet and inspect the control board for burnt spots, cracked solder joints, or damaged relays.
• Test connected loads (fan motor, turntable motor, etc.) for shorts to ground.
• If a relay is visibly burnt or does not actuate, replace the control board (board-level relay replacement is for advanced technicians only).

Recommendation: Due to the complexity and safety concerns, most users should have a professional replace the control board or advise on replacement of the microwave.