Unfortunately, I don’t have a schematic on your model. Can you provide the FCC ID number from the label in the door? Your microwave has three switches. With the door open, two have continuity and one does not. Door closed, one has continuity and two do not. Test the feel of the switches as well. If the microwave runs and is not heating AND switches test good, it is likely one of the thermal fuses, the diode, capacitor or magnetron. These are in the high voltage compartment and are very dangerous even if unplugged. Any strange or different sounds? LG thermal fuses are usually in line and when bad, there will be No power. So that likely narrows it down to the HV section.
