DIAGNOSIS F2 is a temperature sensor fault. The sensor monitoring the cavity or magnetron temperature is giving an out-of-range reading.
FIX Unplug the microwave for 30 minutes to let it cool and reset. Plug it back in. Ensure the vent areas on the back, top, and sides are not blocked. Clear at least 3 inches of space all around.
IF THAT DIDN'T WORK The thermistor (temperature sensor) is likely faulty. It's a small component attached to the magnetron or cavity wall. It requires a multimeter to test and case disassembly to replace.
HEADS UP An F2 error often points to an overheating issue. Do not ignore it. Continuous operation with a failed sensor can lead to magnetron failure or a fire hazard.