Door starts to move then immediately stops; E17 is displayed.

Safety first: Ensure the door is fully supported before disengaging any locks.

Steps:

• Check manual locks: Inspect the inside of the garage door for slide bolts or keyed locks. Fully retract any manual locks before using the opener.
• Inspect automatic lock: If equipped with a Henderson automatic door lock, verify the lock bolt retracts when the opener starts. Listen for the lock solenoid click.
• Free jammed lock: Lubricate the lock mechanism lightly and ensure the lock bar is not bent into the track. Straighten or replace as needed.
• Sensor input: Some models use a lock position sensor. Check its wiring and alignment. If the sensor falsely reports locked, replace the sensor or lock assembly.