I have a Samsung 55" led smart tv. recently it has developed a single horizontal line about 1/4 of the way up the screen. the line goes the entire width of the screen. I am just wondering if this is a problem with the screen itself, or if it could be a problem with one of the boards or a component in a board. If so, how would I diagnose which board or component? pretty much any information would be extremely helpful, as this was a very expensive tv that is not yet three years old. thank you all!!