Home button does not work properly

I have taken my mini3 to get the digitizer replaced by a friend of my wife that owns a repair shop. When i got it back, it seemed like the home button wasnt sitting correctly, and also seemed like it was sliding under the digitizer or lcd. So i took it back, when i got it back again, it worked for a few days then the problem came back. I noticed when i push down on the edge of the front panel i can use the home button. Is there a reason the home button is sitting wrong, its like the button is sitting to deep below the front panel. Is it because he is using the original home button on a third party digitizer? I would like to know, because i want to purchase the correct parts and do this myself.

Thanks