TV volume goes down with out being touched

I just recently encountered the same problem with a Sony Bravia KDL-46EX500. It started out of nowhere but after what seemed to be an update from the cable company. The volume would go down to zero and the LCD light on the front of the TV would continually blink. After trying many "solutions" including resetting the TV to factory defaults, , I removed the batteries from the cable universal remote (Comcast Xfinity) and used only the TV remote and the TV worked fine. When I reinstalled the batteries into the Xfinity remote, the problem started again. So I tried using some of the other codes listed for Sony televisions and found that an alternative code (10273) would also control the TV but not reduce the volume automatically. So, in short, try looking for a different, usable code for any universal remote that you may be using - it may be the problem.

May have a sticky button or a shorted transistor switch.