Replaced display but touch screen not working

I recently had to replace the display due to unfortunate circumstances. The iPhone 4 is now a standalone tool for our grandchildren who love to play games on it when allowed. During the replacement process I used extreme caution to ensure the connections were made in the proper order and uniformly but reverse of the take apart procedure. I had noticed when I powered down the device originally the volume control and touch screen were working both properly. However, now that it is back together the touch screen does not allow the slide open movement. I have taken it apart 5 times, inspected the ribbons and connections to the display, but nothing seems to help. The ribbons are NOT cracked, split or otherwise broken. Any suggestions?