The model number on my garage door opner is 139.53627SRT. It came with the house when we moved in 3 years ago. Couple days back I came home and hit the wall unit to close the door. The door went down half way and started backing up. I looked to see is there was anything obstructing the sensors and everything seemed to be ok. I kept pressing the wall unit multiple times. The door went back and forth a few times and all of a sudden everything stopped working. Now when I hit the button on the wall unit all I hear is a click and the light comes on. I dont have the owners manual. Any help / advice is appreciated. Thanks in advance.