I need a manual for a Mitsubishi TV. The model number is "CK-35306." My son made a large black box appear on the screen. I can't make it go away. If I change the channel or turn on mute or push display, it goes away for a few seconds. Then it comes right back. I tried unplugging the TV and letting it sit over night. But that had no effect either. So I thought maybe it would have something in the manual that could help.