Opener attempts to run but stops immediately; control board LED blinks 4 times repeatedly.

Safety first: Disconnect power and pull the emergency release. Keep people clear of the door path.

• Test door manually: With the opener disengaged, move the door through full travel. If it is difficult to move, call a door professional to correct spring tension and hardware before using the opener again.
• Inspect rail and trolley: Check the Mighty Mule rail for bends, obstructions, or hardened grease. Clean the rail and apply a light, manufacturer-approved lubricant to the trolley slide (not to the belt or chain unless specified).
• Allow motor to cool: If the opener was cycled many times, allow 20–30 minutes for the motor’s thermal protector to reset, then test again.
• Check for binding at header and door arm: Ensure the curved door arm is not hitting the header bracket or door sections. Adjust mounting if necessary.
• Motor evaluation: If the door moves freely by hand and the opener still trips with 4 flashes, the motor may be failing and the motor or entire head unit may need replacement.