Portables that will not Power on.
Go step by step.
Note: Steps 5 and 6
Reset SMC. http://support.apple.com/kb/HT3964
Choose the method for:
"Resetting SMC on portables with a battery you should not remove on your own".
Reset SMC, hold the keys down for 20 seconds or more.
Shut the computer down and try to start it 12 hours later.