Just to clarify: in order to FULLY remove the bottom half of the shell on my PS2 Slim, I had to remove a screw that pinned the controller ports in place; it's at the front, right between the Player 1 and Player 2 ports.
Other than that, this guide worked perfectly! :D
Well, I HAD followed that guide when I disassembled my nN3DS XL. :)
None of the connectors have been physically separated from the board (unless you count the top half of the Circle Pad's connector — the bit that locks down), and as far as I can tell, I've got everything hooked up correctly. :/ But for some reason, it just won't turn on anymore.
I think I'll ask how to get my nN3DS XL working again on that particular guide; it'd probably be more on-topic. :)
Regarding Step 11's attached photo: exactly how ARE those cables supposed to be attached?
Perchance someone could take a photo of their nN3DS XL and show me? 'Cause I was attempting to replace my D-Pad, and now either I hooked something up wrong or (far worse) I broke like ALL of the black ZIF connectors, 'cause my nN3DS XL isn't booting anymore. :(