I have had one of these given to me with the same problem. Screen face down, remove back and screws that need to be removed to allow access to the outer clips that hold the tin shroud to the facia that houses the screen. Isolate the boards so that they can be taken off as a unit still fixed to the "shroud" when the clips are freed. There is a panel at the bottom of the screen that you must also carefully release, I think three ribbon cables. When everything is clear, carefully undo the clips to release the shroud together with the couple of panels that are fixed to it. Now turn over and reveal the LED set up. By looking carefully you may find one or more with black burn marks, if not you can isolate each row of LED's and supply 20v to 30v to each. On mine, three of the strips lit up and brightened with increased voltage. The other two strips never budged. This all went on a few weeks back so make sure you go about it, giving the screen due care. I haven't got round to replacement yet. Good luck, Henry.