DIAGNOSIS The motor's internal reversing relay is engaging, but the DC drive board is not sending power to the motor. A failed capacitor on the logic board is common.
FIX This is a board-level failure. Unplug the opener. The large cylindrical capacitor on the logic board (often 2200uF) can bulge or leak. Inspect it. Replacing this capacitor requires soldering skills. Otherwise, replace the entire logic board (part #41A5027).
IF THAT DIDN'T WORK The motor itself could be seized. Try turning the motor shaft by hand (with power off) through the access hole in the belt cover. It should turn smoothly. If not, the motor/gear assembly is dead.
HEADS UP The logic board contains high-voltage components even when unplugged. Discharge by pressing the wall console button before touching any parts.