Diagnosis
The control board's relay for the heating element is stuck closed. The timer signal works, but the power circuit doesn't break.
How to Fix It
Unplug the griddle. The control board is behind the front panel. Remove the panel screws. Locate the board. Look for signs of heat damage or burned components near the relay for the air fryer circuit. This is a board-level failure. The board needs replacement.
If That Didn't Work
Before replacing the board, check the wiring from the board to the air fryer element for a short. A pinched wire could bypass the control circuit entirely.
Heads Up
This is a critical safety fault. Do not use the air fryer function until repaired. You risk burning your food and creating a fire hazard from unattended overcooking.