perform SMC reset, verify you can boot then:
- Shut down the computer.
- Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
- On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
- Release all the keys and the power button at the same time.
- Press the power button to turn on the computer.
Note: The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC.
If you cannot boot to recovery (CMD + R on boot) then theres a problem and no diagnostics will help
Verify this, if same contact Apple for appt. and full in shop diagnostic and possible repair.