Amana microwave - $20 (La Crosse)

This is my Amana over-the-range microwave, manufactured in 2016.
Sometimes when you open the door, the light doesn't come on and it still thinks the door is closed.
It won't let you heat anything.
But sometimes when you leave the door open for a while, the light will come on inside and it will then let you heat your food.
I'm not sure what's wrong with it, but if you can fix it, you can get it for cheap from me.