I have an Early 2011 13 inch MacBook Pro Model #A1278 running Mavericks. There's a bit of background information that I've got for my problem.
A couple of months ago I suspected that some water might have gotten into my machine and fried the logic board as the display was not working. When I connected the computer to an external display, it would show the grey apple loading screen, and SOMETIMES it would show my desktop background (but only the "extended" part so I didn't have access to my tray or any menus). I took it into an Apple store and they said that the logic board needed replacing because there was corrosion from the water that I suspected. I thought this was a little off because if the video card were compeltely fried then there wouldn't be any images at all showing up on my external device.
My brother-in-law took a look at it and played aroudn with some firmware and it worked fine.
I'm not sure if all that has anything to do with my current problem, but I wanted to provide you with as much information as I could.
A couple nights ago I had my laptop conneted to the TV and the screen slightly opened when my cat jumped on it and slammed it shut. Everything seemed fine and the movie continued to play on my TV. When I unplugged the TV and went to use the laptop, I couldn't see anything. I can confirm that the display does work. When I shine a flashlight through the apple logo, I can see everything. It also works fine on an external device, which I used to confirm that the brightness control is indeed set to maximum. I also tried a few fixes that I found online including those resets where you hold down certain keys during boot up to reset certain systems. Nothing works.
There is one peculiarity that I haven't seen before and I'm uncertain if it's relevant - when I boot up my computer connected to the external display, I see the grey screen with the apple logo, and then it goes to this screen that's mostly white and at the bottom has narrow green rectangles that look almost like a bar graph along the bottom. Looks like something that migth show up when there's a problem with the video rendering process. It lasts for a couple of seconds, and then everything else works fine... my background shows up and I can use the computer normally.
Before I go out and buy a replacement display, I'm going to disconnect and reconnect the wire from the display. I guess it's possible that when my cat slammed it down some connections were severed... but I'm not sure if it's possible for the backlight to be disconnceted but the display still working fine, given it's just one wire connected to the logic board.
I'm wondering if you guys have any other suggestions at what this might be? If it's a software or driver issue that I can fix withotu going through the hassle of replacing the display I'd like to give those a shot first.
Thanks so muchf or all your help!