I fix microwaves for a living, they store over 4 thousand volts in the high voltage section, and if you don't know what you are doing, don't take the cover off.Yours could be one of several problems, if it programs and goes through all the motions but no heat,then you have some type of high voltage problem, that could be a bad high voltage transformer,capacitor,magnetron on rectifier.take it too a pro or have a pro come to your house.good luck