I have a 3g, fw 2.2.1. I cracked the glass and replaced the digitizer. I have tried two known good digitizer assemblies (and have even retested them in another phone so I know they are still good), but the iphone is completely unresponsive to touch (can't slide it on, can't slide it to power off). I have tried resetting (power + home key) 1000 times. I have tried factory restore. I have tried DFU restore. I have tried factory FW and pwned.

I have utterly no idea what else to do at this point? Any ideas what else could be wrong / how to troubleshoot?