Can you boot, at least, to your Recovery partition - holding down the Command and R keys while starting up? If you can get there, perhaps you can try repairing your boot volume using Disk Utility.
If you can't get to your Recovery partition, at least try running the Apple Hardware Test. If you're unable to run the AHT, you're just going to have to take your machine into your local Apple Store or an AASP and have them check it out.
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