When putting the logic board back in place, I recommend placing the DC-in board first and screwing it in loosely. Then, begin lowering the motherboard, slowly lifting the cables up and out of the way as you do so, working from the outer edge, in. Once finished, replace the remaining screws, and tighten down the DC-in board screws.
Also, step #15 absolutely requires the use of a #000 Phillips screwdriver, which also works on all of the other Phillips head screws involved in the install. A #00 Phillips head screwdriver is too large.