This sounds like a problem with the T-CON board. This is the LCD controller board for displaying images on the screen.
Some times the contacts
on the connectors
do not make good contacts for whatever reason.
IF you know how to work on electronics
or have a friend with knowledge/skill you may be able to fix it.
the set and all attached cables.
>Lay the set face down on a cloth covered surface.
> Remove the back cover.
> Remove the shield over the T-CON
> Disconnect AND reconnect the cables to the T-CON
board. Be careful here. The connectors will have a clip which must be released to remove the cable. Hopefully this will clean the contacts.
If it's not fixed, try it again.
If the problem is not solved you can try replacing the T-CON
board. Make sure the part numbers are the same.YOU CAN TEST THE SET BEFORE THE BACK COVER IS RE-INSTALLED BUT BE CAREFUL. IT'S ELECTRIC !!
Replace the shield over the T-CON
Replace the back cover.
Try the set.
You can search for T-CON
The board will look something like;