Apple OS X Yosemite Public Beta Fatal Crash Black boot screen

Update #02: FATAL CRASH 

MAJOR CRASH 3 days in haha.. iMac would not turn on. I put it to sleep one night and it would not turn on next morning. 

When I went to turn my iMac on it loads to a black boot screen with an Apple logo and a progress bar beneath the logo. It loads about 30% of the way and then the computer shuts off. I know it shuts off completely because I have an external hard drive connected and even that power cuts out.

Tried the PRAM reset as well as pulling out all plugs and power with no luck.

Had to go deep forum hunting to find a fix.

I believe the problem was caused by an orrupted and unrepairable / unrecoverable hard disk (1tb Fusion Drive).

To find out how I fixed it:

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