Sudden power loss

Is the internal cooling fan running? (I don't mean the hood vent exhaust fan)

It sounds like your magnetron is overheating, tripping the magnetron thermostat, which protects your magnetron from overheating to the point of destruction.

It may be because the internal cooling fan is bad or the magnetron is just failing.

(Do you hear the cooling fan running behind the control panel when you microwave?)

If you or someone you know decide to look into it, we have critical safety information and disassembly information at our site, and our link is at our listing here on FixYa.

You can usually find helpful exploded view diagrams and order parts by entering your full model number here.

There should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting & testing.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.