We like our new microwave. Replaced our 2015 Frigidaire microwave.  We had it 4 days, used only for heating up beverages and making popcorn but it created a black mark on the back and a couple of spots on the inside of door. Spot and pits on door not there when we installed. I will be contacting customer support.  We have continued to use with no issues. Black mark not any bigger. Spots on door remain the same size. Other than that, we still love our microwave