Touchscreen not working after display change
After dropping my Nexus 4 and breaking the front glas, the touch screen did not work anymore. I decided to change the full display unit (digitizer + LCD). I have now replaced the display unit with a new one and connected everything as it was before. Turning on the phone worked instantly and the new LCD shows a flawless starting screen. However, the touch functionality does not work at all. So now I'm wondering if I made a mistake in reassembling the phone or if the new display unit is defective. Is there anything I might have missed? Or is there a way to test if the problem lies with the display unit or the rest of the phone?
I should note that I got the new display from ebay and while it certainly is new, I assume it's not an original part. I also noticed that my old unit had some sort of shielding on top of the chip that is right above the digitizer connector, my new unit does not have this shielding...
Any help would be appreciated!