2 failed attempts fixing YLOD 3 try worked for 5 mins

Melissa, I think you already answered your own question " I did everything the same on all 3 attempts....The only thing I did differently on the 3rd try was turn up the heat " :-) here is my answer to a similar question. "First you do need to remember that this will only work if your YLOD is caused by solder fractures and if they are not to extreme. Reflowing any board with a heatgun is not an exact science and as such does have a certain amount of failure. The proper fix for this would most likely be a professional reball. Anyhow, the biggest reason for failure to reflow is not enough consistent heat. There is a fine line between reflowing and absolutely melting the solder, so one needs to be aggressive without going over board. If nothing else, get a couple of temperature probes and see what heat you generate. You also need to make sure that you apply the thermal paste properly etc. Follow the guide from here and keep on trying. If at first you don't succeed....:). Hope this helps, good luck.