MacBook not turning on (fan loop)
How is your backup Situation?, if you've got everything backed up, I recommend that you simply format your Drive and reinstall OS X. if you know how, and have the original Disk. If you don't let me know. -quick pointers-

-Insert reinstall CD in your mac.
-restart mac holding option.
-choose from the two drives the Reins-CD
-Boot into it.