Robin Dieker, I do agree with Dan 100%. There is more to a reflow than just to blast it with some heat from a heatgun. There are reflow profiles that should be followed to at least have a chance of a good reflow. I attached a reflow profile for a MBP and that "might " work for you. You should really use at least a decent heatgun and a thermometer to work on it, otherwise you may just end up destroying your board completely. If you do not have the tools or are really not sure, I suggest you should send it off and have it professionally reballed or just the reflow done. Anyhow, Check this link as well as this one. different computer, same work. BTW overheating the board with the towel trick is never a great idea. It puts some extreme stress on your board and your circuitry (I learned that the hard way:-).
"Part's surface temperature
Pre-heat 130～180℃ 60～90sec.
Reflow Over 220℃ 30～90 seconds.
Peak Temperature 240～250℃ within 10 seconds.
Solder composition : Sn-Ag-Cu solder
Hope this helps, good luck.