There are a few warning signs that may indicate that it is time for microwave repair aside from if it simply does not turn on or heat your food. Your microwave could actually still be heating your food but in an insufficient manner.
A lot of other problems have to do with the electrical connections and the circuit board. If you cannot actually program your microwave to function, it could be a circuit board malfunction if you smell a burning smell. Electrical wiring burning should smell much different than the food you have in your microwave.
If you hear a buzzing or clanging noise, it could mean that your turntable is broken or about to stop working properly.
If you come across these issues, it is best to rely on one of our technicians as microwaves use high voltage which could be hazardous.