Hi guys. I wanted to replace the thermal paste in my Macbook Pro 15" Early 2011. I opened up the case as I did so many times before just to vacuum the fans. But this time I removed the board and cleaned the CPU & GPU with Arctic Silver cleaner. Applied thermal paste neatly as described in so many YT videos. I traced my steps back and closed the case. Now the computer runs but there's no light in the screen. I know that it runs because I hear the boot sound, I see the fans running, I hear the click sounds when I hit volume up/down buttons and brightness up/down bottons. So the only problem should be about the lcd screen. However, the lcd screen connecter on the lower left side of the board is neatly connected. I disconnected it and reconnected. But the problem persist. What should I do? Thanks.