S.S.
I recently had a similar experience. I think what happened in our case was that steam from boiling water on the stove condensed in the microwave and shorted it out (you know the thing about water and electricity being bad!) The previous owners of our house installed the microwave, I think, too close to the stove top. We had to buy a new microwave for the counter top and installed a plain hood over the stove for now.