DIAGNOSIS Your opener is detecting an obstruction in the door's path. This is a safety reversal. The three-beep pattern is the standard alert for this event.
FIX First, clear the door's track and floor area of any objects. Check the photo-eye alignment. The small green lights on both sensor units must be solid, not blinking. If misaligned, adjust the brackets until both lights are steady. Test the door operation by holding down the wall button.
IF THAT DIDN'T WORK The door's force limits may be set too low. Press and hold the wall button to close the door. If it reverses, increase the 'Close Force' setting one increment at a time using the opener's adjustment controls. Do not exceed what is necessary to close the door.
HEADS UP Never try to bypass the safety sensors by holding the wall button. The three-beep error will persist until the obstruction condition is fully resolved.