Homebutton stopped working after screen repair

Last week i've been given an iPhone 4 with an broken glass panel. The home button did not work at that time.

I replaced the front screen and turned the phone on. Like many screen repairs, mine started flickering and I waited patiently. After some time the screen flickering became less so I could try the screen. But now something weird happens.

The home button worked. Not very well, but it responded multiple times while using it. It turned the screen on when touched en closed the apps and so forth. (note; The screen still had some flickering)

I went to sleep and let the phone rest over night. When I woke up the flickering was completely stopped and the screen worked very well.

Thing is though, the home button stopped working. It would not respond at all.

Does anyone have an explanation for this? Or an solution maybe?

Piet.