Rca tv volume keeps cutting down.

volume keeps cutting down. Have to use remote for the cable. It will not cut volume back up but if i keep pressing the up on the remote, a message comes up on the screen about warranty date and hours. I have no idea how to stop this. If i go to menu, the volume stays up until I close menu, then it goes right back down. I can only cut it up with the volume control button on the front of the tv.