Sony D-242CK discman buttons issue

Hi there, I found this page while looking for solutions on how to repair my Sony Discman ESP D-242CK. Since I got it, everything had been functioning well, but a while ago the on/off button (also the start/pause button) started to deteriorate — to the point where I had to press it several times to turn on the Discman. Obviously, this was something bound to happen.

Right now, the button doesn’t work at all, and I’m no longer able to turn on my Discman. It has sentimental value to me, so I’m trying to repair it.

Does anyone have any advice on how to fix buttons on this model? I’d really appreciate it if you let me know. Thanks for reading!