Microwave will not start; display shows E1 immediately after pressing START.

Safety first: Unplug the microwave before any disassembly. High-voltage components inside a microwave can retain a dangerous charge even when unplugged. Do not touch the capacitor or magnetron area.

Step-by-step checks:

• Inspect the door: Open and close the door firmly several times. Check that the door sits evenly and that the latch hooks fully engage the cabinet. If the door is sagging or misaligned, gently lift while closing to see if the error clears.
• Check for obstructions: Look at the door latch openings on the front of the cabinet. Remove any food debris or plastic that might prevent the latch hooks from fully inserting.
• Test door switches (for experienced DIYers only): Remove the outer cover (usually screws on the back and sides). Locate the door switch cluster near the latch. Using a multimeter on continuity, test each microswitch while pressing the actuator. Replace any switch that does not change state (open/closed) correctly.
• Check switch bracket: Ensure the plastic or metal bracket holding the switches is not cracked or loose. Tighten screws; if the bracket is warped or broken, it must be replaced.

When to stop: If you are not comfortable working around high-voltage components or cannot access the switches safely, stop and contact a qualified appliance technician.