I punched in the time needed and hit start and there was a loud pop that sound like a fuse blew. I waited and tried to start it again--it came on but didn't heat up. I called Whirlpool and spoke with a representative. I was told that it sounded like the magnetron has gone bad--does this sound right? If so--is it better to replace the the magnetron or buy a new microwave? How much is the part and can it be installed by an license electrician?