Stuck on grey screen after internet restore My early 2011 MBP 15 stopped loading one day and is stuck on the grey screen when I start it up.  


I have changed the hard drive with a formatted one (that I did on my
Mac Pro) to the journaled file system 
cleared the NVRAM reset SMC
tried booting from a restore USB I created with OSX on it (wouldn't
load) 
replaced the thermal past on the heat sink 
tried to run in single user mode to diagnose firmware problems but now it won't boot into single user mode holding CommandS no matter what I do, it just
keeps loading to the folder with the question mark (no operating
system yet on the new hard drive)


I can get it to start the Internet restore except it gets to the point where the Apple logo comes up, with the spinning wheel below it, then the screen flashes black then grey and stays grey forever.

I have gone through every thread I can find on this and am now lost.  The last idea is to reload the firmware but I haven't found exactly how to do that yet, or at least check it to see if it is corrupt.  Any ideas on how I can get into single user mode?  Any ideas as to what is going on?
My iMac 2011 had grey screen hanging like yours - same exact issues. I also wiped out my hard drive, internet recovery would hang, turns out both RAM sticks in my iMac went bad at the same exact time. Replacing those fixed the issues for me.