Screen does not work after installing new power button

I have replace two iPhone 5 power buttons now and both times I have managed to destroy each screen in the process. The first had a bunch of lines going through, and the second was just white with a large black bar on the left side.

I would like to find out what I am doing wrong. I have done many screen replacements and I've yet to encounter a similar issue. In fact, I used a cracked screen I replaced to test these phones to isolate the screen as the issue.

Some how I'm apparently damaging the screen somewhere in the process, but I'm not sure where. Any help would be very much appreciated.

Thanks!