After hitting the remote repeatedly, all you get is flashing lights. This causes you to get out of the car and close the door from the wall button inside the garage. A garage door not closing combined with the flashing lights will be due to the safety reverse sensors not working properly.
Safety reverse sensors are mounted at the bottom of the garage door tracks on both sides. Safety reverse sensors are responsible for making sure there is nothing under the garage door as it closes. In 1993, the UL325 code was enforced requiring every automatic garage door opener to have safety reverse sensors installed. Safety sensors can safe a life, consequently they can be quite a nuisance at times.
In order to diagnose this problem you will look at the safety reverse sensors. You will have two sensors, one will be green indicating the receiving sensor, the other will be amber, indicating the sending sensor. The sending sensor with the amber light should always be lit. The green sensor therefore, will not be lit if the eye beams are not aligned properly.
In order to align the safety sensors, look to see that they are pointing directly at each other. Move the brackets back and forth to see if the receiving light goes off. This will tell you if they are not aligned close enough. Adjust the safety sensor until you can move the bracket and the light will not go off.
A non-working sending sensor will indicate either a wiring problem or probably a mal-functioning safety sensor. Check the wiring at the motor head to make sure the wires are connected. If all is well at the motor head, check the wiring connection at the safety sensor.
Malfunctioning safety reverse sensors should be replaced immediately. In the event that you cannot replace them immediately, you can bypass the safety reverse sensors by pressing and holding the wall control button down until the door fully closes.