Diagnosis
Total power loss. The most common culprit is a blown thermal fuse on the main control board, which is a safety device that trips if things get too hot inside.
How to Fix It
Unplug the microwave and check your kitchen circuit breaker or GFCI outlet first. Try plugging a lamp into the same outlet to confirm power. If the outlet is live, the issue is internal. For this model, the thermal fuse is often located on the magnetron's thermal protector or near the vent duct. You'd need to open the cabinet to test it with a multimeter for continuity.
If That Didn't Work
The main control board itself could have failed, often due to a shorted component or a power surge. A dead control board will have no signs of life and usually needs replacement as a unit.
Heads Up
The high-voltage capacitor inside can hold a lethal charge even when unplugged. If you're opening the case to check the fuse, you must know how to safely discharge the capacitor first.