DIAGNOSIS This is a control panel or main board lock-up. A power surge or static discharge can cause it.
FIX Unplug the air fryer from the wall outlet. Wait for two full minutes. This allows the internal capacitors on the main board to fully discharge, resetting the microcontroller. Plug it back in. The screen should initialize normally.
IF THAT DIDN'T WORK If it's still frozen, perform a hard reset. Unplug it. Press and hold the power/temperature button on the panel for 30 seconds while it's unplugged. Then plug it back in. If that fails, the control membrane or main board has a hardware fault.
HEADS UP Always plug the appliance directly into a wall outlet, not a power strip. Power strips with surge protection can sometimes interfere with the appliance's soft-touch controls.