Phone completely died while trying to replace screen. Other issues...

I have an iPhone 5s which the touch was being really temperamental after I'd lent it to someone and they dropped it. I bought a replacement screen off Amazon.

I got it all apart and tested the screen alone as the included instructions said. Screen worked great. When I properly assembled with the metal back and camera/speaker and whatnot, I couldn't get an image but could see the back-light through the edge. I tried to reseat the connectors a few times but the little square sticker that attached to back of the screen (I assume ground?) snapped off. Would this cause a big issue? The screen worked fine without it.

While I was inspecting it a bit more the phone fell of my desk onto carpet. It wasn't hard but the camera came out a bit. I put it back into position but the phone no longer shows any life. Has no power, won't charge and isn't recognised by a PC.

What have I done and can it be fixed?