Are you saying the door will open okay but when you try to close it the door reverses to the open position and the main light flashes 10 times? If so you once again have a sensor problem. Make sure they are pointed directly at one another and the small light on each one is on.

Could it be that something is hitting the sensors to make them misalligned? We had a similar problem with brand-new garage door & opener. Quickly realized that if the walk-in door swung all the way open it tapped the sensor & after 2 or 3 times it nudged the sensor enough to make the garage door not want to close.