Today, I attempted to boot the MBP (it had been in shut down since last night) and for the first time since I discovered the SMC reset temporary workaround, it would not work. Grey boot screen (with the same horizontal striations as per usual) then apple logo (horizontal striations bleed over the apple logo) then grey screen and nothing. No keyboard backlight, no response from caps lock key or contrast or anything. Fans start purring at about the interval they would had I been able to log in and boot the OS. But still only grey screen.
So I shut down and attempt the SMC reset. For those who have never reset the System Management Controller, it is not difficult. After shutting down (if you are not able to log off and shut down, ie the os is in an absolute freeze state, holding down the power button for 10 seconds will do the trick) you must make sure that the Mag safe power connector is attached (and lit) and then press (Left-side)SHIFT-OPTION-COMMAND and the Power Button simultaneously and release simultaneously. The led indicator on the mag safe power connector will (in my experience) flicker from green to amber and back to green, when an SMC reset is successfully completed. I have also noticed a very subtle 'pop' noise, perhaps from the speakers?
Anywho, I have had to perform this function about 4 times since the problem first presented itself this weekend. Today, this time, the SMC reset does not work… Basically, attempting the SHIFT-OPTION-COMMAND+I/O Button does not incur the 'pop' nor cause the LED to flicker, and thus I am unsuccessful attempting to boot afterwards. I try my steps a second time and still nothing.
It occurs to me that I am waiting to witness the led "change state" (flicker from green to amber) and that it is usually amber when I am attempting this (this is because I am often using the MBP while it is not plugged into AC power, and so I have to plug-in in order to initiate the SMC reset.) Because the MBP has been plugged in all evening, it has a full charge and the LED is green, therefore I cannot witness it "change state" to green. This is just a passing thought because it would be very silly if a SMC reset could only be initiated when the battery is partially depleted. Nonetheless, I unplug the MBP and this time after shutting down. I attempt a NVRAM/PRAM reset (which is successful) and then a SMC reset. Voila, I have a working MBP again.
Now, I appreciate your response Hal Freidman, and I am realistic and understand that over 400 pages worth of fellow mac users (some of which are no doubt far more hardware savvy than myself) have attempted to wrap their heads around this problem. But the whole scenario and all of the evidence collected here just buggers belief. I understand that many of you have gone over this every which way and that many of you are convinced that there is a physical explanation for this epidemic (eg the lead-free vs leaded solder balling on 2011 MBP GPUs) and that definitely stands to reason. But to me, my personal experience so far defies this explanation. How can resetting the System Management Controller fix this problem (even if it is merely only a temporary fix?) Unless someone can describe to me how my understanding of physics here is flawed, I have a hard time accepting how resetting something within a computing system on a software level could affect something as macroscopically physical as the soldered connections of the GPU. Unless of course, resetting the SMC is forcing the MBP into using the integrated graphics chip rather than the discrete… That is possible, I suppose. I admit I do not know enough yet about the nuances of the system at play, but accounts such as DIESEL-X's "BOOT DISK Partition/Selection Screen" displaying properly only further fuel my curiosity and belief that something more complex is at work here.
Lastly--and I apologize for this TL/DR manifesto--I have had a very similar thing occur with this very Late-2011 MBP 15 (8,2) before… a malfunction that seems in every way hardware related that is 'magically' fixed by changing something in firmware (or software, rather, in this case.) For anyone interested in reading that account it can be found here (https://discussions.apple.com/message/24964949#24964949) or by googling "black magic MBP 2011."