Progress bar gets halfway before the screen goes grey
I seem to be having an almost identical problem except I'm using a 2011 27" iMac.
What I find strange is that trying to boot from external drives with mac partitions result in the same behaviour: progress bar gets halfway before the screen goes grey.
I have tried the single user mode approach and the FSCK fy command but that doesn't seem to have sorted it either.
It seems as though I may just have to open the iMac up and replace the drive...
Is dit een goede vraag?