EDIT: I have solved the issue. Please see my last comment in the thread for the solution if you are having the same issue.
Hi all,
I recently purchased one of the UV Printed shells from retro game repair shop for my GBA SP. I put it together and everything is good, but after I put everything together, the d-pad is pretty "mushy". It mostly applies to the down key. It feels fine when I don't put the back cover on (I even loosened the screws that hold in the motherboard), but the moment I put the back case on, the buttons feel weird. The up key feels fine, but the down one doesn't feel good at all to press. I tried to loosen the screws on the back cover, and it makes it better, but it still doesn't feel good. It really only feels normal without the back cover. Does anyone know of a fix?