1 - 2 horas
Got the dreaded and unexpected yellow light of death.
It took me forever because I was a bit too careful and had to attempt it 3 times. I did not want to mess anything up. My first attempt failed. It lasted for about 10 secs. It started fine, then the fans went crazy and it ylod again. I tried it a second time. I thought maybe I didn't heat the board long enough since the other tutorials I read said to heat it for longer and with more heat. I did it longer the second time. Again, it lasted 10-15 secs and shut down. But this time, it didn't seem to ylod. I received a message that it was too hot and will shut down. I then took it apart and realized it was the heatsink not touching the chips properly. I bent the clamps and added a thermal pad to the clamp for more pressure. I finally got the heatsink to touch the chips a bit more. Still wasn't to my liking, but there was nothing I could do short of getting something like copper plates. Started it up, and it worked. It was able to last long enough for me to save my old data. It still works, but I don't know for how long.
First off, I would like to give kudos to ifixit's customer service. They sent me a defective screwdriver handle. I sent them a message and got a replacement part sent out right away. Love that kind of service.
Ok, in terms of the actual repair, you may not want to use all the thermal pads that are included with the kit. So keep your existing thermal pads! I only used the large ones and a few smaller ones and the rest were wasted. I found out they were too thick and would not allow the casing over the system board to close properly. While it seems to close correctly, it actually does not allow the heatsink to touch the cpu and gpu chips completely. Mine was not even touching the cpu at all which was the cause of why my first 2 attempts failed.