Garage door will not close from remote or wall button; opener light flashes once and the door reverses to open position.

Safety first: Disconnect power to the opener before touching wiring. Do not work under a moving door.

Steps to check and fix:

• Inspect the photo-eyes: Locate the Motorlift safety sensors mounted near the bottom of the tracks on both sides of the door. Make sure both LEDs are lit solid (usually green on one side, amber on the other).
• Clean the lenses: Use a soft cloth and mild cleaner to remove dust, spider webs, or debris from the sensor lenses.
• Realign the sensors: Loosen the wing nuts on the sensor brackets. Gently rotate each sensor until both LEDs stay solid. Tighten the wing nuts while keeping alignment.
• Check wiring connections: At the opener head, verify the thin low-voltage wires from the sensors are firmly connected to the SENSOR terminals (often marked with white/black and white wires). Tighten any loose screws.
• Check for damage: Inspect the sensor brackets and wires along the wall for kinks, staples through the wire, or cuts. Replace damaged sensors or wiring as needed.
• Test operation: Restore power and try closing the door with the remote. If the door closes and the light no longer flashes once, the issue is resolved.