home button acting weird and falling out

It's a refurbished iPhone, presumably there was a screen replacement (judging by paled colors compared to my iPhone 5s with an original display). The button worked fine at first until I dropped the phone (the hit came on the top edge, the screen haven't been broken). After that Touch ID and the button functionality still works but now button reacts on any touch and doesn't react to pressure difference. I mean, it's enough to slightly touch it to have a response. I had to turn off Siri because it was activating faster then Touch ID.

In addition to that, the button have separeted from the screen and I can pull it out half way with something sharp.

Did anybody had something like this or does anybody know what is the problem?

So, i finally got my "Y" screwdriver and opened up my phone to try to fix that issue.

What I found out is that my "button" was probably replaced/repaired during refurbishing process. I think so, because it's not in one-piece anymore (steel cover on the back side of the button is separated from front side, where it is supposed to be welded). I tightened that screw anyway. But I can't confirm that it worked as intended, because I've cut one of the screen connecting flat wires

while trying to slide screen down to separate it. I guess that wire was responsible for 3D touch and home-button, because I lost 3D Touch, Touch ID. Home-button still works but now it's completely unusable (now it requires unreasonably hard press to get a response).

Is this cable replaceable, and if so, where can I buy it?

Should I make a separate question about it?