How can I fix my GE Microwave?

GE PROFILE CONVECTION/MICROWAVE- Model #PVM179OSR1SS History of the problem: My microwave was dead. I called for GE service and was told to turn off the power and turn it on again, it didn't fix it. An electrician confirmed that the power was going to the unit. The GE repairman said that we needed to replace the WB21X10148 thermostat, and we sent for one and replaced it. All the lights and fan work now but the microwave does not. When the door is opened it says" Caution-oven hot". What else do we need to do to fix this?