you know when it says do not turn off your computer it means do not turn off your computer. I understand waiting 12 hours is really gay but you might have fucked up your windows install and might need to reformat.
I found something that might help you
When W8 won't boot
Difficult to access anything without an Installation disk or Repair disk/drive. You could repeatedly try shift plus F8 at power on and you may get into Safe Mode. Meanwhile, if you have access to another machine running W8, create a recovery media. A small USB flash drive would suffice, the files only require around 250 Mb. Type 'Recovery' at the Start Screen and choose Create a Recovery Drive from Settings. Uncheck the box for Recovery Partition if you have little space, ie small USB flash or CD. Once created, insert drive/disk in the failed PC and change the boot order in BIOS accordingly, USB boot or DVD/CD .
Once booted, navigate to Advanced Options and try Recovering to an earlier date, or from the Command Prompt try sfc /scannow followed by enter
If that fails consider Refresh your PC.
this website also shows some commands you do when you boot the bios.
http://answers.microsoft.com/en-us/windows/forum/windows_8-system/windows-8-is-stuck-in-an-automatic-repair-loop/2310c795-d39b-460f-9e4c-c95008e5ce51