Diagnosis
The thermal cutoff fuse has blown. This is a safety device that trips if the unit overheats, often from a blocked air intake or a failed fan.
How to Fix It
Unplug the unit and let it sit for at least 30 minutes for a full cool-down. Check that the air vents on the back and top are completely clear of any obstructions (wall, cabinets, towels). Plug it into a different outlet. It may reset and turn on.
If That Didn't Work
The thermal fuse is a one-time safety part. If it blew, it needs replacement by a technician. The root cause (like a faulty fan motor) must also be fixed.
Heads Up
Always leave 5 inches of clearance on all sides, especially the back. Operating it in an enclosed space guarantees overheating and fuse failure.