Stuck on Grey Screen During Startup I updated to Yosemite on Saturday and everything has been working fine, I have been able to shut down and startup as normal until today.

A couple of days ago I forced my Early 2011 MacBook Pro to shut down and now it will no longer get to the login screen.

I hear the chime, the Apple appears with the Yosemite status bar underneath, it takes a long time to get about halfway then both the Apple and status bar disappear leaving just a blank grey screen.


I can get into Single User mode, using "fsck -fy" it reports that everything is OK.
I can't get into Safe Mode, I just get the Apple and status bar followed by grey screen
I have reset PRAM
The Internet Recovery globe and status bar appear followed by the Apple and status bar then grey screen
Holding Option I can select my disk but there is no Recovery Disk displayed. The image of my hard drive that appears has a custom icon that I haven't used for at least 5 years which is very odd indeed.
I have a bootable Yosemite USB, holding option I can select that but it just brings up the Apple and status bar then grey screen.


So basically everything other than Single User mode ends up at a blank grey screen.

I'm at a loss, any help would be greatly appreciated.

NOTE
My left fan is faulty, I have ordered a new one online. I have been using SMCFanControl to monitor it, if the computer has been feeling hot I have been increasing the RPM for a minute to cool it just to be safe until the new fan arrives. Last night I increased the RPM and SMCFanControl became unresponsive which is why I forced the computer to shut down because I couldn't reduce the fan speed back to normal.

Early 2011 MacBook Pro, OS X Yosemite (10.10)
It is already become usual when new OS update finally break defective GPUs.

You didn't state what exact model of early 2011 you have but if it is 15" or 17" it just may be it since Radeon HD in those models tend to break.

If yours MBP is indeed with Radeon GPU try to use towel method i.e. wrap it into bath towel (dry of course) after startup and let it sit and become really hot. Try to restart after it. If it working you might try this approach