If your garage door does not close completely or closes and then starts to move up, the travel limit switch issue may be the cause. You can adjust them with a few tools. The sooner the better, as this situation may cause serious safety issues.
To start with, you need to identify the kind of limit switches your door has. If your door opener has a screw drive, it is very likely that the spring loaded switches turn the motor off when the carriage reaches them. It is possible that there are trip arms or clips attached to the opener chain (they may be repositioned). There is a number of models where adjustment screws are located on the opener itself.
If the door reverses unintentionally when fully closed, adjust the switch so that it stops the door sooner. In case the door, vice versa, does not close fully, you will have to adjust the switch so that the door seals.
In most cases it is obvious how to adjust travel limits once you see the switches. If you are in doubt, refer to the owner’s manual. If you happen to have lost your copy, you will probably be able to find it online and download it, provided you know the make and model of the opener.
Warning! Test your garage door
If the UP and DOWN travel limits are set incorrectly, the safety reversal system often fails, and people (especially children) could be injured or killed. Having made any adjustments, test the safety reversal system. Lay a 1-1/2″ high (or 2 x 4 laid flat) object on the floor and see whether the door reverses. If this does not happen, resolve the issue.