Hi there. I've just had the exact same issue this evening. As I had purchased a glass/digitizer only in first place (which I couldn't manage to install without destroying the original LCD as it is glued to the digitizer), I was able to push the diagnosis a bit further. -When booting with the LCD/digitizer assembly connected, the digitizer is totaly unresponsive. I suspected a flex cable damage or ESR damage to the digitizer chip, althought I am an experienced repair guy with all the proper equipment. -I then turned off the phone, and swapped the digitizer connector with the Glass/digitzer I had purchased before, just to make sure the problem was not coming from the logic board of the phone. And the glass/digitizer worked fine. -Now with the phone still powered on, I hot swapped the two digitizers, and the previously not working digitizer started working. It all stops working when you reboot the phone. -I have double checked every connector related issues and tested continuity on all traces. Hardware...