Door goes all the way down, stops and then goes up again.

The problem is probably the opener safety sensors. Inspect the photo-eye sensor. The sensors are the small black boxes the near the bottom of your garage door frame which are usually installed on the tracks with a small bracket.
When the infra-red sensors are malfunctioning, usually one of the sensor lights will be blinking. The problem is either due to a blocked path between the sensors, dirty eyes, loose wires at the sensors or at the motor head, or just bad sensors. The transmitters (remotes) will not work to close the garage door. You will find that the door will only move an inch or so in the close direction and reverse. When this happens your garage door will only close by holding down on the wall button, or wall console, until the door fully closes. This method is the only way to override the safety and close the door.
1. Make sure that there is not something blocking the sensors from communicating with each other and the wire connections are securely fastened at the sensors and motor head, and the eyes are directed at each other. A lot of the time dust, spiderwebs, or even a small toy can block the sensors. If there is anything blocking the sensor remove it and try your door again.
2. If there is nothing blocking the sensors they maybe misaligned. They need to be pointed at each other in-order for they to work . If they are try to push alignment sensor into alignment. You will know they are aligned when the light stops blinking on the sensor.
3. Also, try unplugging the garage door opener and re-plugging the unit back into the outlet. This acts as a reset and may reset the sensors. If nothing works, it may be that you have to replace the sensors.