I had many problems with the DC-IN : the LED changed color all the time from green to orange, and I had to try moving the DC-IN so that it works, pulling on the wire in every directions, but sometimes the computer just shot down and it was such a mess…
I followed the installation guide and everything was really easy ; eventhough the number of screws was not accurate for my computer, after the inside shield was removed, and I found less screws than written on the tutorial, it was even easier. I also had 2 screws on the DC-IN, not only one as indicated.
You should be careful while opening the computer, because some parts (clips) seem to be quite fragile. You need the right tools at this very moment.