DIAGNOSIS The opener's travel limits are incorrectly set. The unit is stopping and reversing because it thinks the door has reached its fully open or closed position.
FIX Reprogram the travel limits. On the motor unit, press and hold the 'Learn' button until the LED blinks. Immediately press the 'Up/Down' arrow button once. The door will move. When the door reaches the desired fully open position, press the arrow button again. Repeat the process to set the closed position by pressing the arrow when the door contacts the floor.
IF THAT DIDN'T WORK The issue may be a faulty control board not retaining the limit settings. Disconnect power from the unit for 30 seconds, then reconnect and repeat the limit setting procedure.
HEADS UP Ensure the door is balanced manually before setting limits. Disconnect the opener by pulling the red emergency release cord. The door should stay in place when lifted halfway. If it falls, the springs need adjustment by a professional.