Well last day of Christmas break, my 7 year old throws in some microwave popcorn. No idea how long it was in, but I thought the house was burning. Microwave interior black, after cleaning its now more of a light brown. Did the vinegar/water steaming and it still smells. Last night my pillow even smelled like it. I’m sure some of the residual smell will disappear, but every time microwave is run it lets off more. Any ideas?