DONT PAY FOR A REPAIR! its not worth it anymore, as most companies dont replace the gpu because the part isnt made any more. They don't repair it and it isnt permanent, but your still paying!! its crazy! fortunately there is a way to do the exact thing that they do without dissassembling your computer! just follow these steps:
1. Plug in your macbook pro (make sure that its off)
2. Turn on the computer, and hwen it chimes, close the lid and turn it updside down.
3. Wrap the macbook in a heavy quilt.
4. Let the computer sit for about an hour.
5. Take it out of the quilt, unplug it and let it cool for 20 minutes.
6. Turn on the computer.
I can say that this works as I had the same problem, and after this method, the computer is up and running, I'm typing this on it now!