Microwave displays F5 and will not start; sometimes appears after a power surge or during high-load cooking.

Safety: Disconnect power. Microwaves contain high-voltage components; do not probe or power the unit with covers removed unless you are a trained technician.

• Power cycle: Turn off power for 10 minutes to clear transient faults. If F5 returns immediately, suspect the control board.
• Listen for relay click: When starting a cook cycle (before the error appears), listen for the relay click from the control board. No click or repeated clicking may indicate a bad relay.
• Visual inspection: Remove the control panel and inspect the electronic control board for burnt spots, cracked solder joints around relays, or melted areas.
• Check for overheating: Ensure cooling vents and internal fans are not blocked; overheating can stress relays and the board.
• Replace control board: If the board shows damage or F5 persists, replace the electronic control board (PCB) with the correct Monogram part. Transfer any jumpers or mounting hardware from the old board.

Note: Component-level repair of the control board (e.g., replacing individual relays) is not recommended for most homeowners.