Hey, brilliant kids can still take instructions very literally. I know -- I have a 17 yr old one. LOL

Anyway, my MW char experience was gingerbread scones put in -- we thought on convection and they micro'd for 9-10 min. They didn't look so bad, until the door opened and they flashed. We let baking soda sit in there, heated water with baking soda as well as water with lemon juice. That was before Febreeze -- don't know if that might help (the air freshener or a sheet in the room near it -- not sprayed inside) break it up sooner. In our case, it improved pretty well, but we'd still get some of it when we used the MW again for a while. It did eventually go away.

I also googled microwave with burned smell and found a whole list of sites and remedies. Might look and see what appeals to you.

vinegar, lots of vinegar. Put it in a mug with water, heat it, dump it out. Do it over and over....like a million times. Also, wipe the inside of it with a vinegar-water combo too. Also, wipe it down between the mugs of vinegar "tea".

I know it's horrible, and this probably won't get rid of it completely. We had a "potato incident" in ours. For some reason a baked potato went crazy in our mw once. After only 5 mins it was smoking like crazy, fire alarms, dogs howling, this all happened not too long after the microwave was installed. There was no way that this appliance was going to be replaced again so soon. Even today, if someone microwaves something for a few minutes there is the hint of the smoke smell. At least we don't smell it when we walk past the mw any longer!

Good luck! And yes, my gifted child is my biggest challenge too, and he is almost 19!

TY TY TY!
I will try both but not at the same time. I think I had heard of both remedies in the past but then again, baking soda and vinegar seem to be great for a lot of things ;)
I used some cleaner on the walls of the mw earlier, but I know it is in the fan section and do not want to use a lot of chemicals anyway.
If he had had more chili in the cup (paper), it would have boiled over and been a huge mess, but by the time I figured it out, it was a solid lump of black and the cup was black on the outside up to the chili level. Scary!

I may be dense, but when you said 15 did you really mean 15 seconds. Nothing heats in 15 seconds. I agree 15 minutes is too long but 15 seconds seems way too short. I'm not sure this is your son's fault - sorry.

There were only a few bites left and he wanted to heat it up a little while finishing it. 15 seconds would have been plenty. He has never made that error before. He will ask and I will tell him "20" or "hit the minute button", etc... If in doubt, he is pretty good about asking until today. He was just rewarming while in the middle of eating it. He also is impatient so any longer and he could hit a very hot spot.
If it had started from cold and/or was a full cup worth (from Wendy's), it would have been less of a problem.

Weismann,

My MW could scorch in 15 seconds. Melt a stick of butter in
30 seconds. I think 15 sec was wise so her son would not
burn his mouth.
Weismann, forgive me, I sound grumpy, I need my coffee.

Dianalo,
You are not alone, I have kids, incompetent relatives
and a sweet husband who forgets the Mircorwave's power.
When such a horrific stench happens I wash my MW with 1/2
cup vinegar and 1/2 cup of water. Washing the inside, the
glass turntable tray, the walls...

Then dry the MW. Take a new small box of baking soda open
it and let it sit in the MW all night long. Some sources
recommend 24 hours but with a houseful of teens this won't
happen in my kitchen. Rather I leave the B-Soda until the
morning.
***Be sure to put a note on the MW that the kitchen is
closed until morning.

This should work because your MW is not damaged but rather
a little too stinky.
~boxer

As a last resort, you can have the cavity liner replaced, if the MW is worth repairing. I had that done once after a roommate cooked a bag of popcorn for 30 mins instead of 3 mins.

Oh, memories!

Get a large shallow pyrex casserole dish and cut up 3-4 oranges or lemons into quarters and place in the dish. Cover with 3-4 cups of water and place in the MW on high for a 10 minute boil. Yes, it will boil over, and that's fine. The citrus/water solution will vaporize into those crevices that contain the yucky smoke and will eat up that smoke smell. It will also loosen any cooked on "bits" that may have exploded onto the roof of the MW.

This works on a smaller scale to clean out a dirty MW also. Halve a lemon and put it into a measuring cup of 2 cups of water and cook for 3-4 minutes. Let stand and steam, and wipe out the MW while it's still warm.

I am working on the vinegar one as I type and plan on trying the baking soda one after I get a new box from the store. My dh had told me the lemon trick a little while ago too, so that is on the shopping list as well :)
Thanks for all the good advice. It still is pretty stinky, but we moved it upstairs in the larger space, so hope that it clears up soon. I was getting nauseous from the smell last night as I went to bed, so got up and relocated the whole mw.
It was worse after the first batch of vinegar "tea" and each one after seems a little better. I wish I could dunk the whole mw in a bleach and water solution, but if I did, it would only work as a paperweight after that, lol!