My garage door opens fine with the remote or the button. Will only close by holding the button down. I have unhooked the sensors and have disconnected the door from the opener and have the same problem. The sensors or door drag have been bypassed. What should I try next?
As longneck described, it sounds like there is something interrupting the beam that detects if an object is in the way of the closing garage.
If you look at each end of the garage opening near the ground, there will be two little "detectors." They're typically attached to the rails that the garage door travels up and down on. One of these detectors shoots a "beam" across to the other. If this beam is broken, or never gets back to the detector that shot it out, the door will think something is in the way and won't close properly.
Chances are there's nothing actually in the way and instead, one of the detectors got bumped out of alignment. You should hook all of the wires back up how they were and then check the sensors for alignment. You should be able to fairly easily bend them on an axis to get them to point at one another. Most sensors have a small LED light on them that tells you if they can see one another... play around with the adjustment until the LED lights are lit up and then try your door opener (or closer) again.