Microwave will not start; display works but pressing START does nothing or beeps three times and shows E01.

Safety first: Unplug the microwave from the wall outlet before any disassembly. Microwaves contain a high-voltage capacitor that can retain a dangerous charge even when unplugged. Do not touch internal high-voltage components (capacitor, transformer, magnetron). If you are not experienced, contact a qualified technician.

Step-by-step checks:

• 1. Basic reset: Unplug the unit for 5 minutes, plug back in, and try again. Open and close the door firmly several times, then press START.
• 2. Inspect door alignment: Check that the door closes evenly and that the latch hooks fully engage the cabinet. Look for bent or loose latch hooks on the door and damaged latch openings on the cabinet.
• 3. Check for obstructions: Make sure no food debris or warped door seals are preventing full closure.
• 4. Door switch test (for skilled users): Remove the outer cabinet (after unplugging). Locate the door interlock switch cluster near the latch. Visually inspect for burned, cracked, or loose switches and connectors. Using a multimeter, test each switch for continuity when the door is closed. Replace any switch that does not change state correctly.
• 5. Harness and mount check: Ensure the switch bracket is not loose or bent and that all spade connectors are tight on the switch terminals.

When to stop: If the error persists after confirming the door closes properly and switches are intact, or if you are unsure how to safely access the switches, stop and call a professional technician.