Welcome to the forum, sorry to hear about the microwave. I had an Amanna or maybe it was a Tappen that did the same thing. They are all pretty much the same. If you remove the screws and take off the top and sides you will mist likely find the main fuse near where the power cord enters the case. Mine had one of those old screw in type, like houses had before circut breakers. The bad news is, my gun was shot and new fuses blew also. You do not want to run the unit with the covers removed, they do provide shielding. I hope you have better luck with yours.
Wally Byam Airstream Club 7513