If your computer won't turn on, try each of these steps:
1. 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.)
2. Make sure that the power adapter is properly connected to the power port on the side or back of the computer.
3. Disconnect all accessories that are plugged into the computer, such as a printer, hub, or other mobile device.
4. Reset the computer's PMU, SMC, or PRAM. Refer to
these instructions.
5. Try plugging a different power cord into the computer (if you have a working one available). If the computer starts up, replace the old power cord.
6. If the computer uses a power adapter, try connecting a different power adapter to the computer (if you have a working one available). If the computer starts up, replace the old power adapter. (Computers that use a power adapter include MacBook, MacBook Pro, iBooks, PowerBooks, Power Mac G4 Cube, and Mac mini.)
7. If you tried all of the steps above and the computer still won't turn on, contact Apple technical support (1-800-APL-CARE in the U.S.) or take your computer to the nearest Apple Store or Apple Authorized Service Provider for diagnosis. If you plan to visit an Apple Retail store,
make a reservation at the Genius Bar.