Just last month this was tracked down to a failed LED backlight. It's not trivial to fix. So here's an example of what you are in for.
1. A primer on such work. http://imgur.com/gallery/Yol8M In this case you are unlikely to solder but I add this, just in case.
2. The video!
Hey all--I searched the forums but didn't find a similar question. A buddy just gave me his old LG LED TV, but it has large dark shadows in an upside down L shape. Almost like a Tetris piece.
I've searched forums, tried solutions from YouTube videos, and more, but nothing has worked. Here's a pic of the screen.
http://i64.tinypic.com/296gd9c.jpg
Any help is appreciated. Thanks!

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