My better half decided to dry a garden plant in the microwave oven.
Unusual humming from the oven and when the door was opened... smoke and a burnt plant.
Inside top panel of the oven was hot, burnt and buckled.
Cleaned up the inside top and the buckled panel relaxed (so did I).
Tested the oven heating a couple of times with cups of water and all seems ok.
Why is there no fire/thermal sensor fitted to a microwave oven?
Small 'Sharp' brand. Couldn't see any label on the back.
There wasn't enough smoke or other products of combustion to set off the dining room fire detector.