mgtjr53

My TV no longer responds to remote, has no display lights on front and will not respond to any buttons on side panel (except for one, more later).The only way I can turn it off is to unplug it. That means I am unable to access the self-diagnosis function. The only button that it responds at all to is the "Input" button on the side panel but once that screen appears I am unable to make changes to the input because as soon as I push any other button, including the input button, that screen disappears. I am connected to a Cox cable box and am able to watch those channels, it is basically a monitor now. I have to unplug the power to turn it off and it comes back on after plugging the power back in but nothing else changes even after leaving it off for 24 hours. I have a service manual but nothing in it for this situation. Any help out there for what the possible problem is? Thanks for any help available. I am capable of replacing a board if I know for certain which board is the problem.