i had the same problem with the Touchscreen, because one of the ribboncables didn't wont to work. I tested several positions for the cable and after 3 hours of testing i got it work. Sorry for my bad englisch. (I don't now if it was cable 1,2 or 3 but all of these cables has to be in a perfect position to work).
If this solution didn't work you can try to clean the contacts of the three cables (be careful because you will have to clean it with liquidcleaner, it can broke your whole iPhone). And then dryness the contacts with a Hairdryer, but be careful, the iPhone should not get warm, so only use a low heat.
I hope i could help you a little bit.