DIAGNOSIS This is almost always a thermal overload. The internal thermal fuse blew to prevent overheating.
FIX Unplug the unit immediately. Let it cool completely for at least 60 minutes. Check the rear air vent for blockage. Plug it directly into a wall outlet, not a power strip. Press and hold the Temp/Time knob for 5 seconds to reset.
IF THAT DIDN'T WORK The main control board may have failed. Listen for any faint hum when plugged in. No sound at all means a dead board or power supply.
HEADS UP This is a serious safety shutdown. Do not attempt to bypass the thermal fuse. If resetting doesn't work, the unit needs professional repair or replacement.