Diagnosis
The drive motor is energized but the gear train is disengaged. This is a stripped plastic drive gear, part #41A4253.
How to Fix It
You must replace the main drive gear assembly. Unplug the opener. Remove the cover. Locate the gear case on the motor. Remove the old gear assembly, noting the worm shaft alignment. Install the new gear kit. Reassemble and test.
If That Didn't Work
The motor capacitor could be weak. A faint hum with no gear movement points to a bad capacitor. Test and replace the 300-350µF run capacitor.
Heads Up
Do not force the door manually when the gear is stripped. It can damage the gearbox further. Always disconnect power before opening the unit.