hi everyone. i've had this garage door opener for a few years now and recently one of the remotes stopped working for one of the doors on my garage out of no where! i thought it was a problem with the battery so i switched it with another remote but no response. i noticed that the green LED button that opens the garage is blinking constantly. that button works, but the remote for the door doesn't work. i cant seem to find the instructions manual either. help is appreciated!