If the picture on your TV flickers, there may be a simple fix. Here are some possible answers and suggested solutions:
1. Your set-top box may need a simple reboot. Unplug the power connection to the set-top box for about 30 seconds. Reconnect the power and turn the set-top box back on.
2. Check all of your cables for a loose connection by tightening each one with your fingers.Flickers can sometimes be caused by bends in rigid cables, too.
3. If your picture flickers to a black or blue screen, you could have a bad set-top box. Contact your cable or satellite service provider about installing a new one.
4. If you still have audio, the flickering could also mean that you have a failing backlight.
For additional troubleshooting information, check out the chart at TV flickering
for more solutions. I hope this helps!