A few years ago, I had this same problem. I fixed it by removing the touchscreen flexi, soldering 4 mod wires on to the main flexi, then I fixed them onto the touchscreen using epoxy. I then used conductive paint to make a connection between the wires & the silver tracks on the touchscreen. Worked great until the screen was cracked a few weeks ago :-(
Good news though, I have now fixed it again, details in the next post.