Use the emergency release handle to release the door. Run the opener to the open position until it stops. Close the door until it stops. Now re engage the the door.
It sounds like you may have a problem with the eyes at the bottom of the door jam. These two eyes must be aligned so the light from one is picked up by the other one. Sometimes they get bumped by accident and need to be re-aligned. Check at the top of the eye where it is touching the metal bracket. If it has been moved the plastic pin on top of the light sensor will be out of the hole in the metal bracket. carefully move the plastic light body until it snaps into the hole on the metal bracket. Then try the remote. If that doesn't work, check both boxes on each side of the garage jam. one should send out a light beam and the other one should receive it. Try this. In the dark put a piece of paper in front of the unit that is NOT sending out light the beam. Line up the light beam with the receiver hole on the side of the unit. move it around until it shines into the eye on the side of the other unit. Try the opener. See if solves your problem. If I get to a point like this where nothing I try works I get out a tool that always fixes anything, my checkbook. Good luck. :)
Sounds like a problem with the safety photocells, to confirm locate the where the safety input is on the opener and bridge out the terminals ( not the supply voltage terminals) if the door then closes the photocells are the problem.
Inside the car press the 2 outer buttons on the homelink until the led light by it goes out or flashes rapidly. This erases all old/factory codes. Hold the remote 1" from the button you want to program and press the button on the remote and the homelink button until it flashes rapidly. Then press the learn button on the motor head and then press the button on the homelink you pressed before 4 times and this should code in. Thanks BB
Question edited for clarity.
Question moved from Cars and Trucks category.
Look at the corners of the doors that hold the aluminium frame together and if it is a modular door, tighten them up. If it is a solid door, adjustment can be made by shimming behind the bottom hinge with a piece of cardboard. This will move the bottom out and up.
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Check the opening limit dial on the garage door opener unit. You can locate the dial that controls the opening limit on the opener unit and use a flat head screwdriver to turn the dial counter clockwise until the door stops about an inch and a half away from the stop bolt. Then, test the door and make sure it does not slam into the bolt. A video tutorial on how to adjust the opening limit of a Craftsman garage door opener is available on YouTube.
If the above step does not work, check the limit switches on the garage door opener. Most garage door openers have limit switches that control how far the door opens and closes. Improperly adjusting these switches can cause the door to stop halfway. Consult your garage door opener's manual to learn how to adjust the limit switches. Make small adjustments until the door closes fully. Craftsman garage door opening too far and hitting stop bolt easy adjustment (youtube.com)