How to Access Parts for Repair - No heat

Everything seems to work, but there’s no cooking heat. We smelled burned electric insulation or burned electrical component.

I have a multimeter and have worked with many electrical and electronic appliances. How do I access the magnetron and other parts of this over-the-range wall mounted microwave oven? Do I have to remove it from the wall?

Is there any capacitor I need to discharge before removing the magnetron?

Is the Invertor a suspect more so than the magnetron?

Thanks in advance.

– Mike