Microwave display shows E4 and unit will not start; sometimes appears after a power surge or lightning storm.

Safety: Unplug the microwave before removing any panels. Avoid touching exposed circuitry while plugged in.

Steps to try:

• 1. Hard reset: Unplug the Tower microwave for at least 15 minutes to allow capacitors on the control board to discharge. Plug back in and check if E4 clears.
• 2. Check power source: Plug the microwave directly into a wall outlet (no extension leads or multi-way adaptors). Verify the outlet voltage is stable using another appliance.
• 3. Inspect control panel ribbon: If accessible from the front (some Tower models allow keypad removal), gently reseat the flat ribbon cable between the keypad and control PCB.
• 4. Visual inspection (advanced): With the unit unplugged and outer cover removed, inspect the main control PCB for burnt components, bulging capacitors, or signs of arcing. Do not power the unit with the cover removed.

Resolution: If E4 persists after a reset and wiring checks, the main control PCB or its EEPROM is likely damaged and must be replaced. This is typically a board-level repair best handled by a technician familiar with Tower microwave electronics.