I've got a Dell Vostro here, EFI boot. Windows 8 and it has got stuck in a repair loop after a powercut in the office.
There's not that much info around about fixing EFI boot problems but I have tried what i know from repairing Windows 7 plus what little I have found online.
chkdsk says no problems,
sfc /scannow reports Windows Resource Protection cannot start the repair service.
also failed to work. Rebuildbcd seems to find the OS but gives a - The requested system device cannot be found when trying to add it...