Clean your microwave with white vinegar or Mr Clean Magic Eraser then put one drop of vanilla extract (imitation is ok) on a rolled up paper towel and let it sit inside a couple of hours (make sure it doesn't touch plastic sides it will stain them) and then remove the paper towel, the vanilla smell will disipate and so should the burned smell
I would wipe it out with white vinegar
I spray the inside with an odor remover like Frebreeze.
White vinegar is a great deodorizer, you could use it full strength or half and half with water.
An alternative is baking soda and water with a few drops of dish soap. When not in use you could air it out or leave a box of baking soda in it to absorb the smell.
Microwave a bowl of vinegar for a minute and let it steam in the microwave for a couple more minutes. Then wipe the whole thing down.
Wipe it down with white vinegar
Yes, I agree, white vinegar gets rid of so many smelly problems. I sometimes spray it in the air as an air freshener. The vinegar smell goes away in a few minutes along with the offending odor you're wanting to be rid of.
Have tried vinegar, still getting smell. Also did baking soda. Smell not as intense, but still there. Will repeat to see if it will resolve.
Boil water with lemon juice in the microwave and let sit until it cools down completely. Then wipe down the steamed sides with paper towels...repeat if necessary.