⚠ Safety note: This guide involves working with electricity. If you're not completely sure about every step, stop and call a licensed professional. Before you start, always switch off the power at the breaker or close the main water/gas valve.
1 Prepare for safe operation
Unplug the appliance, close the water supply if there is one and wait for the hot parts to cool down. Prepare the manual of the correct model and a dry work surface.

⚠ Warning: Do not open part with mains voltage, capacitor, magnetron, heater or cooling circuit. Such diagnostics must be performed by a qualified service.
2 Determine the condition and cause
Check if the timer, overheating protection or automatic pan recognition is activated. Record the time until shutdown.
3 Perform a key check
Use a flat magnetic pan of the appropriate diameter, clean the controls and clear the cabinet ventilation under the plate.
4 Do a repair or maintenance
Test one zone at medium power. Multi-zone shutdown, blown fuse or repeated error, call an electrician or service.
? Tip: Take a photo of the initial state and change only one thing at a time. This will make it easier to determine what actually solved the problem.
5 Test the result
Return all available parts and run a short supervised test. If leakage, sparking, smell of burning, or discharge of protection occurs, turn off the device and call for service.

When to call a professional: If the job involves changes to the electrical panel, the main gas line, or load-bearing walls/beams — or if you're not sure how it will turn out — this is not a DIY task. Hire a licensed professional.