This forum deals with a desktop/tower 65lb Mac Pro
Direct you to the proper forum for MacBook :Mac OS X Help
Isolating Issues in Mac OS
Get Help with your Product
printing in OS X Mountain Lion
Mac OS X & Mountain Lion Community
Startup Manager: How to select a startup volume
Troubleshooting: My computer won't turn on
If your Macintosh computer won't turn on, here's how to troubleshoot it. Please keep in mind that although your computer may display similar symptoms that prevent it from showing video, this article discusses what to do if the computer won't turn on, meaning that when you press the power button:
- You don't hear a startup chime.
- You don't hear any fan or drive noise.
- The power button or power indicator doesn't light up at all.
- You may hear a startup chime.
- You may hear fan or drive noise.
- You may see the power button or power indicator light up.
ResolutionIf your computer won't turn on, try each of these steps:
reset SMC For "Mac wont' turn on or boot" and related
- Make sure that the power cord is plugged into a working wall outlet, and that it's properly connected to the power adapter. (To check if the wall socket is working, plug in a lamp or other electrical device.)
- Make sure that the power adapter is properly connected to the power port on the side or back of the computer.
- Disconnect all accessories that are plugged into the computer, such as a printer, hub, or other mobile device.
- Reset the computer's PMU, SMC, or PRAM. Refer to the instructions for your model:
Note: It is possible that the SMC could encounter an issue that may cause unusual system behavior typically related to the symptoms described below. In some cases, resetting the SMC may be the only correct method to resolve the issue,
General purpose Mac troubleshooting guide:
Creating a temporary user to isolate user-specific problems:
Identifying resource hogs and other tips:
Starting the computer in "safe mode":
To identify potential hardware problems:
General Mac maintenance:
I suppose it's a LCD back light failure.
You need to replace back light or whole LCD.
PS/ You'd better ask about your problem at MaaBook Forum