Why is my iPod touch screen unresponsive after replacement?

These digitizers are very, very fragile.. Plus, when you install the ipod 4 digi, you should rewrap the connector with the copper tape that was originally on the connector and wrapped around to the front of the logic board. I know that the stickum was probably bad, so what I do is use a small piece of double-sided 3m tape to reattach it.

If the connector is not taped in place properly, even moving the screen a bit could be enough to dislodge it. Sorry to say, but if I had to guess you are going to have to take it apart and double-check the digi to mb connection, and make sure it is tight.. If all this is done, then there is a possibility that you might have flexed the cable to the point to where it came loose at either end of the connections, and ruined it., Hope this is not the case, but I have done it more than once..

With all the ipods and iphones, handling the digitizer is extremely tedious and the more you handle them outside the case, the more likely you are to break something. These connectors and cables are not engineered for repeated maintenance. That is, they are set to work and stay where they are for the life of the product...