My Mitsubishi WS-55511 is 4 yr old. It worked fine until a couple of weeks ago after plugging in an xbox. Now the tv won't respond to the remote. It turns on when using the power button on the panel, but when I go to the device screen to try to change, it won't go away from the device menu and the tv won't power off with the power button. I tried resetting and unplugging, but no change. Does anybody know what the problem is?