Unplugged unit, Tested all the thermostats after bleeding off any existing voltage. Found the thermostat at the top of microwave that rests against the ceiling of microwave had gotten a piece of food stuck to it and caused it to overheat. The contacts were melted. Cut wire, crimped on new leads, replaced thermostat and unit fired right back up. $5 fix. Took about 35-45 minutes to take microwave down, take off shroud and rewire and replace thermostat.