My screen went black with faint horizontal lines, I knew it was turning on, so I figured the screen needed replaced. I decided to do the repair myself because I run across your site with instructional videos and cost associated with dealing with The Apple Store; minutes I would never get back or at my pace and leisure..a no-brainer.
The initial install went great and after I had gotten it all buttoned up. The screen would turn on but would not work via touch or anything. After researching the issue, it is apparent many have had the same conclusion, yet no actual confirmation of an appropriate solution. I decided to go back through the phone; unscrewing, disconnecting, and reconnecting each point. I took my time. With a fine tipped object and my finger I connected each ribbon until I was sure the connector was seated firmly. Once seated I realized they "bite" and are not so easily unplugged ,as they were when installing. I strongly think it was my home button connections that were not seated, so pay special attention and take your time there.
So make sure all connections are good and firm!!!! This immediately and officially fixed my touch screen, the phone works like new.
Take your time (especially the Home button) and make sure each ribbon is connected firmly, it should not be so easy to unplug if properly seated.