Just a thought, you haven't accidently started pressing "TIMER" instead of "COOK" have you?
How embarrassing...I've done that. but at least I'm candid enough to admit it. ;-)
"There's mines over there, there's mines over there too, and watch out those goddamn monkeys bite, I'll tell ya!"
Dont mess with a microwave oven unless you have years experience with electronics. There are parts inside that can shock you or kill you if you touch wrong parts when they are charged up. Some can retain charge even when unplugged. Besides that, new microwave ovens are so cheap, its not worth fooling with. If you do manage to fix it, you may have disabled a safety function... such as a door-open-shut-off switch. Very dangerous. If you decide to mess with it... do lots of research on HOW to do it and what to watch out for.... but I think it is a bad idea to mess with. (PS... i am an electronics technician 30 years experience).
Check fuses VERY VERY carefully, apart from that, its probably scrap. Steve
+1 Yep, and remember there are a lot of goodies that can be salvaged from a wasted microwave.
+1 sad to say, but that's part of the modern experience. You *might be able to fix it, but it is likely less expensive to just buy a new one.