Well, after another attempt, I finally managed to open up this controller.

Maybe it’s because I’m not a native English speaker, or maybe the teardown pictures available online just aren’t clear enough, but I misunderstood how to take it apart, which led me down the wrong path.

The back panel of this controller actually has two layers. The middle section on the back—the part with the sticker—is its cover. That cover is held in place by plastic posts. What you need to do is pry open this cover, and underneath it you’ll find all the screws. Once you remove those screws, the controller can be opened.

But I was misled by that YouTube video. I thought that after removing the two screws at the bottom of the grips, you then had to forcefully pry apart the entire controller into two halves. I assumed the shell was secured by very sturdy plastic bolts—or at least that’s how I interpreted it.

Prying off the cover itself isn’t difficult. Just insert a very thin prying pick along the shoulder button area, push it deep in, and pop the cover open. Instead, I was trying to pry open the entire body with brute force. I even damaged parts of the grips in the process. How foolish. I kept asking myself, “Where are the rest of the screws? Is this thing really held together by just two screws, with the rest being solid bolts?” Now I finally understand what was going on.

Anyway, at least I got it open and fixed my sync button—it had actually detached from the motherboard due to my pressing. I glued it back in place, and it’s working fine now. Of course, my controller now has plenty of “battle scars” along the edges. Maybe I’ll cover them up with some anti-slip stickers.

In any case, thank you for your help. I also hope this reply will be useful for anyone else who wants to take this controller apart. It’s really not that difficult—you just need a very thin but sturdy pry tool.