It no longer heats when in cook mode but...

it sounds like either the magnetron is faulty or some part of the hv side is shorted .the pop sound is the fuse going and this normally means that something has shorted out.if you have a multimeter you can test all the hv side to see if there are any shorts.give me a email with what you find and i will be ablke to give you a better idea from there .hope this helps,regards les