Microwave is completely dead: no display, no lights, no response when buttons are pressed.

Safety first: Unplug the microwave before opening the cabinet. Internal fuses are not user-serviceable in some regions; check local regulations.

Step-by-step checks:

• 1. Verify outlet: Test the wall socket with another appliance to confirm power is present.
• 2. Inspect power cord: Look for visible damage or burns. Replace the cord if compromised.
• 3. Access internal fuse: Remove the outer cabinet. Locate the mains fuse near the line filter or where the power cord enters.
• 4. Test fuse: Remove the fuse and check continuity with a multimeter. If blown, investigate for underlying faults (shorted components) before replacing.
• 5. Check thermal fuse: Locate the cavity thermal fuse and test for continuity. Replace if open, using the correct Grundig-rated part.

If a new fuse blows immediately or no obvious cause is found, stop and contact a technician, as there may be a shorted transformer or other high-voltage fault.