Replaced screen but now doesn't work

I've been trying to repair an iPhone 5s screen and battery. First I purchased a cheap replacement screen off Amazon. It didn't work, so I also purchased a battery off iFixit. Connecting the battery and screen to test showed instant signs of life and the phone was up and running! I disconnected the screen and started adhering the battery to get the phone ready to put back together.

When I plugged the screen back in to test for a second time, most of the touch stopped working. I cleaned the connectors with rubbing alc and a toothbrush, reseated them, and got an entirely blank (not lit up) screen.

This continued no matter how many times I tried to reseat the cables. I could feel the phone heating up so I knew that it was actually powering on. I tried disconnecting the battery as to shut down the device but this was to no avail. I inspected the connector on the display and noted that the connector to the left of the three had some damage in the center. I opted to replace the screen with an iFixit screen, which just got here today. I seated all the cables, and I am getting the same results of no signs of life.

I would like to mention that in my attempt of putting the screws in to seat the bracket that goes over the display connectors, I unfortunately put the wrong size screw and broke the holes off....How could I come back from this? I'm now thinking to invest in a magnetic mat from here to better keep track of screws instead of just throwing them all together....Mistakes were made, lessons hopefully learned here.