Diagnosis
A blank screen with some power (like the fan might run) points to a failure in the controller unit itself, or a loose connection to its display.
How to Fix It
Unplug the grill. Open the control box on the back of the hopper. Check the main wiring harness plug that connects into the back of the controller PCB. Unplug it, look for any bent pins or corrosion, and plug it back in firmly. Also check the smaller ribbon cable or wire bundle that connects the front display—reseat that connection too.
If That Didn't Work
The controller board might have a blown capacitor or other component, often from a minor power surge or moisture. If the connections are good and the screen is still dead, the whole controller assembly likely needs to be replaced.
Heads Up
Before you decide the controller is toast, make sure you're checking the right power source. These need a proper 120V outlet, not an extension cord or a weak outdoor circuit that's dipping in voltage.