My grandson burned a bowl of ramen noodles in my microwave.

Search internet for vinegar and baking soda formulas. I would start with a mixing bowl of 1/2 cup vinegar in 1-2 cups of water. Run microwave on medium temp for maybe 45 secs. Let set for vinegar to absorb and repeat. Do not boil over! May be able to scrub with a baking soda formula, but that is an Ajax and could damage interior. Both products safe and natural and remove odors. Baking soda w/vinegar in garbage disposal and bathtub best thing I ever learned in the last 20 years.

https://www.youtube.com/watch?v=jRWzvLI0ZD8

try watching this

I use a bowl of vinegar or a lemon cut in half. Here is a link for more!

http://m.wikihow.com/Get-Bad-Smells-out-of-a-Microwave

Mix apple cider vinegar and water in a microwave safe bowl or cup, and microwave on high for fifteen minutes. Then take that out and put a shallow, wide container of baking soda in and leave it all night. If that doesn't do it, I give up.

Using a Pyrex measuring cup, fill with half water and half vinegar. Or apple cider vinegar. Set for two minutes on high. Be Careful when removing the cup because it could be hot. It might smell like vinegar for a couple of minutes, but that pretty much should take care of it. Also the steam that this method puts out is an excellent way to get the greasy food and residue off the inside of your microwave.

Fill a bowl with 1/2 cup water and 1 tablespoon white vinegar. Heat for 5 minutes and let it sit with door closed for 15 minutes. Next, remove bowl and wipe the insides dry with a paper towel. Repeat if necessary.

Let it air out, run lemon water for 3 minutes, wipe it out, repeat, then let it air out again.

I am assuming you have cleaned out any spills and nothing is in it. Then take a cup of water and 2 Tbsp of white vinegar in a microwave safe bowl. Put that in and shut the door, microwave for 5 min. Keep the door closed and allow the steam to do it's work for 2-3 minutes. Then very carefully remove the bowl and wipe everything down inside the microwave.

The remainder of the water/vinegar can be used to clean around the house where there are odors.