Can't pass by apple loading screen I own a 17inch MacBook Pro late 2011.
While working on Photoshop I experienced a screen distortion with vertical strips and then it got stuck. I was forced to restart but I couldn't pass by this screen.



I tried everything. Resetting PRAM, checking disk in Single User Mode (sbin/fsck -fy), I was able to mount a drive and back up my data. Sometimes, I was able to boot normally, but I had the same issue again after a while. Finally, after many attempts, I was able to boot in recovery disk and reformat my os, I did a clean install. At first it seemed to work fine and I upgraded, all happily, to El Capitan.
While still testing the Mac if was working properly, I had the same issues again. Now, no matter what I try, it refuses to do anything except Single User Mode.

What's wrong? Is it the logic board? Is there something I can do? Unfortunately, Genius Bar is not an option as I moved away from uk.
The problem was solved by replacing the logic board. I went to a local merchant who complies with Apple, and they told me they will replace it for free. After being pressed by its customers (in US) who were complaining for this issue and even sued the company, Apple filed an issue for free replacements during the last five years.
More info here and here