Chosen Solution
I don’t have Xfinity, I have a Direct TV DVR. The dark half of screen still is present when I try a DVD player through a different port. I’ve recently reset the DVR box due to a problem related to a lightening storm power surge. The dark started at top of screen and seems to be creeping slowly down screen. Does this mean I have a bad TV?
@cmoore3575 possibly that this is a bad LED backlight strip. For that you will have to disassemble your TV and the LCD panel. Not a fun thing to do but possible. Of course you do want to check all the wiring, specifically the wiring on the power board. Let us know what the exact make and model of your TV is and what you have tried to fix it.
If you’ve PHYSICALLY powered AND UNPLUGGED EVERYTHING connected to your TV, as well as swapped HDMI cables around,,, AND your issue remains then I am afraid your issue may be HARDWARE related in your TV itself. But before you go to BEST BUY or your favorite TV store… try to see if you can run your TV in DIAGNOSTIC mode … and see if you can bring up color bars. if its a newer SMART TV, it should not be too hard to get it to a diagnostic screen from the setup menu. If the issue is still present when in drag mode…even after unplugging and powering up your TV again… Im afraid you might be out of luck. MIGHT be time for a new TV or a visit from a TV repair person.