How to fix garage door sensor blinking green?

A blinking green light on a garage door sensor means the receiver sees the infrared beam from the sender intermittently, which the opener treats as an obstruction and refuses to close the door. The fix sequence is alignment first, then cleaning, then wiring. Loosen the wing nut on the green receiver sensor, gently rotate it up, down, left, and right until the LED stops blinking and stays solid, then retighten. Wipe both sensor lenses with a dry microfiber cloth to clear dust, cobwebs, or fingerprints. Make sure no rake, bike, or storage box is between the two sensors. Check the small bell wires running from each sensor up to the opener for staples, cuts, or loose terminal screws. Sun glare on the receiver can also cause flickering.