Undo the top screw and add some plastic tape around the spacer that comes out. In my case, I used packing tape since it has a strong-ish adhesive. If you cut it thin enough, it isn't noticeable when put back together.
All 3 screws on the outside took the same bit. The one I used was generic and didn't have the size written on it. You can see more screws inside, which I didn't undo.
I could not take it all apart since the display was stuck in, and I couldn't access the connector on the board.
The top encoder is its own assembly and can be removed without undoing the top screw. However, if you want to replace the wheel, you will have to disconnect the top assembly entirely and dismantle it. Unlike the bottom cap, it is stuck in with some tape and will take some prying. It is connected by a ribbon cable to the main board, which is easy to dis/connect.
Buttons are mounted from inside and just fall out once you slide the main board out enough. They should be easy to replace if you want.
I'm not a modder or a repair tech, but I hope this is helpful to someone looking to get started on mods/repairs for these.
This was made for a university course on game development. A lot of the projects I saw used AI so I felt proud about drawing all the art for this (animation/tileset etc) . It didn't seem to make much impact though.