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

Safety first: Unplug the microwave 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) unless you are trained and know how to safely discharge the capacitor.

Step-by-step checks:

• 1. Inspect the door closure: Ensure the door closes fully and evenly. Check that the latch hooks on the door engage smoothly with the latch openings on the cabinet. If the door is sagging, gently lift while closing to see if the error clears.
• 2. Clean the latch area: Food debris around the latch can prevent full engagement. Wipe the latch hooks and the latch openings with a damp cloth and mild detergent, then dry thoroughly.
• 3. Test door operation: Open and close the door firmly 10–15 times, then try to start a short cook cycle. If E01 intermittently clears, the door switches or latch bracket are likely worn.
• 4. Access the door switch assembly (for experienced DIYers only): Remove the outer cabinet screws and carefully lift off the cover. Locate the door interlock switch cluster near the door latch. Visually inspect for broken plastic actuators, loose screws, or burned switch terminals.
• 5. Check switches with a multimeter: With the unit unplugged, remove one wire from each door switch. Set the meter to continuity. Operate the door latch by hand and verify that the primary and secondary interlock switches change from open to closed as the door closes. Replace any switch that does not change state cleanly.
• 6. Reassemble and test: Refit the cabinet, tighten all screws, plug in, and test with a cup of water for 30–60 seconds.

When to call a technician: If the door appears misaligned or the latch bracket is cracked or loose inside the cabinet, professional replacement and alignment are recommended to maintain radiation shielding integrity.