Garage door close up to 1/2 of the garage

Sensor must show steady light to close circuit and let opener work. If aligned, then there is a loose or broken wire. Try reaiming first to get steady light. Then check all wires . Another way to test and prove that is the issue is if u hold down the wired button at ur back door and the opener closes, then it is sensor issue. Good luck.

disconnect motor, check the door is operating smooth and correct. check springs. check downward pressure setting

Adjust the position of the door by using the black and purple buttons. Black moves the door UP (open) and purple moves the door DOWN (close)
Setting the up position: 1. Press and hold the black button until the LED starts flashing slowly, then release. 2. Push and hold the black button until the door reaches the desired UP (open) position 3. Push the door control or programmed remote control. This sets the Up (open) position and begins closing the door. 4. Immediately when the door begins to close press and release the black or purple button. This will stop the door Setting the Down position: 5. Push and hold the purple button until the door reaches the desired DOWN (Closed) position. 6. Once the door is closed, If there appears to be too much pressure on the door, you may toggle the door back and forth using the black and purple buttons to reach the desired closed position. 7. Push the door control or programmed remote control. This sets the Down (closed) limit and the door should open.

Check your door sensors. Make sure they are pointed at one another and the small light on each one is lit and not flickering ever so slightly. Tweak them a little. If you cannot get both lights to come on you have bad sensors.

It could be the garage door motor that is acting up. Try closing it with the button in the garage. If that's not the case, you may need a different garage door opener.

I can't help you on programming.
If the door goes up as soon as it touches down, it is going too far down.
Locate the adjustment on the box on top. There should be four adjusters:
Door down amount more or less
Door up amount more or less
Force down more or less
Forch up more or less.
Turn the Door down amount toward the "LESS" or "-"
Let me know how you do.
Gary

Check your door sensors. Most likely one has been bumped and they are not pointed at one another. Tweak them until the small light on each one is lit steady and not blinking.

My service shop says that the sensors can go bad and still have the lights on steady. Also sun lite on the receiver sensor (green led) can cause a problem or if they have gotten wet.

Play with the alignment and if still a problem new sensors are about $40 a pair. Or if you have another door that works OK, swap the sensors to see if that is the problem.

check the safety photocells is theres not obstacle between then, check both photecells leds are on.. otherwise no need to replace them

try adjusted the sensor controls on the sode of the unit other wise replace the logic board
http://www.chamberlain-garage-door-openers.com/circuitboardcompatibilitychart.htm