Yosemite update frozen screen

I have spent about and hour researching this and it looks to be an issue that others have had.

I have tried several of the suggestions mentioned (trying to open in safe mode, holding down Shift-Command-P-R, and just trying to restart.)

Nothing is working. The grey screen appears, it gets to the half way bar point, and stops.

Last night I tried to install Yosemite. I went to bed when the bar stalled at half way, thinking that surely in the 7 hours or so I slept, it would finish.

Nope. It got stuck at the halfway point and stalled.

It will not open in safe mode and I cannot get to any screen of any kind to install, uninstall, or anything of the like.

And, as luck would have it, my Applecare is out of warranty as of 5 months ago. It is a 2011 iMac.

Thank you for any help you can give me.

Dawn

Looks like my 3rd attempt to open in safe mode worked. It is taking several minutes to load anything at all, but it is finally in safe mode.

I will leave it on, although I need to be away from the computer for a few hours.

Did you run Disk Utility before attempting the installation? It sounds to me like there may be some problems with the hard drive.

No, I did not run a disk utility before installing.

If you have run Disk Utility already try that now. Make sure you verify the drive and make any recommended repairs. Make sure you verify the drive rather than permissions. Although it won't hurt to repair permissions as well but it probably won't hurt.

Thank you.

I rebooted and it looks like it is working now?????

I have NO idea what I did. I just deleted a few things and tried it.

I will see about running a utility disc utility as well and hope it all stays working.