Chosen Solution
I posted a few weeks ago about my screen flickering - was told it was the LED Display Driver Board that needed replacing - so I did - I bought 2 just in case, and the first one, no change, second one, same, no change either. However, now the display won’t turn off - ever. The computer boots up, very white screen, then goes to the gray screen and all is normal. Except - to shut down, it acts normally but then goes from black to white as the hard drive shuts down but the display stays on - all white again. It only turns off when the battery is removed. I have done resets (hold the power button 10 secs, remove battery etc.), restarted with the PR, Opt, Comm Keys, etc. etc., nothing seems to work. Again - I still have the same issues with shadows so I know the LED display driver board is not working properly, I will replace it with the original one today and contact the people I bought the new ones from - but the display itself will not shut off unless the battery is removed. If I put the computer in Sleep mode, it turns black for a split second, then flashes back to white again.
OK, this does not sound good here ;-{ From the sounds of it your GPU and/or Controller chip is now failing again. Here’s someone else which is facing a similar problem which I explained fully the history of the GPU problem: Weird. Sometimes get horizontal lines at boot, sometimes no.. In this case if you got the extended warranty repair done you should have the second rev chip. Here the solder between the chip and the logic board is failing. Looking at this image: Logic board we can see the three chips with solder paste. Two of these chips were made by Nvidia: the GPU and the system controller. Both had issues with solder breakdown.
