MASSIVE PROBLEM HERE!
First things first, thank you so much for such an excellent guide. I replaced the magsafe apparently successfully, since when I plug the charger in, the orange light lights up immediately (first green, then orange).
However, I did break a couple of those delicate sockets as I went through: the fan and the rear speaker ones, and now the computer doesn’t start altogether! I don’t know if it is because of those two broken components or because I screwed up somewhere else during the process, though.
I’ve tried gluing the plastic housings back in place in the hope the pins would actually made contact, but it hasn’t made a change. The computer still doesn’t respond.