I noticed the cooling coils (evaporator) in the freezer section was completely caked in ice and figured the defrost heater was broken. I defrosted the cooling coils with a hair dryer and found the defrost heater element to be burned in half, so it was useless. I ordered the part and it amazingly was delivered in less than 24 hours. I installed the new defrost heater element and the refrigerator works again.