Front Panel replacement having issues

Well... I'm not sure where I went wrong. I had a broken glass screen, so I had that replaced. Unfortunately, there wasn't any instruction about the metal plate needs to be transferred... and that threw a curveball. I lost one of those tiny screw holding the plate. However, I got it in working order and it worked great for only ... ONE DAY. When I got home, I spotted the missing screw and decided to get it back in the metal plate. Unfortunately, I accidentally ripped the home button cable... nothing beats the "oh no..." sweat perfused on my body. So I had to wait a week until I get the replacement. At last, it has arrived and I managed to get them all connected (yes, properly seated)... it's still not powering on. Even disconnected the battery cable to do the power cycle. It's STILL not powering on. Where the heck am I going wrong? Also, I noticed one of the screw was missing from the plate that covers the connectors behind the camera area (the lower left). I know I put it in before. Is that why?