In February 2015, Apple launched its “MacBook Pro Extensive Repair Program for Video Problems”.
The page of recall says:
Apple has identified that a small percentage of MacBook Pro systems may experience distortion, lack of video or unexpected reboots. These MacBook Pro systems were sold between February 2011 and December 2013.
Apple or an Apple Authorized Service Center (AASP) will repair affected MacBook Pro systems free of charge.
At the end of February 2016, when the program was due to expire, Apple decided to extend it until December 31, 2016 or up to three years from the original purchase date.
Yesterday, the page of recall has been updated once again with two changes: first, all 2011 MacBooks Pro are removed from the program; Second, the deadline is now up to four years from the original date of purchase, for MacBook Pros 15 ″ Retina models from mid-2012, or 15 ″ Retina models from early 2013.
If you have one of these laptops that has video distorted or scrambled on the computer screen, no video on the computer screen (or external screen) even though the computer is on, as well as unexpected computer reboots (kernel panics), check its coverage on the Apple website.
Do not waste time.