What does the 10 flash signal indicate on my garage door opener?
According to this site, 10 flashes means the door sensors have detected an obstacle.


  When properly connected and aligned, the sensor will detect an obstacle in the path of its electronic beam. If an obstruction breaks the light beam while the door is closing, the door will stop and reverse to full open position, and the opener lights will flash 10 times


Depending on the make and model of your opener, this may be what's causing your problem.

Depending on the sensors, there might be lights on the sensors. Check the manufacturer's documentation to determine what the color and/or status of the lights should be.