My friend's iPhone 5s has a similar issue: Water damage, and even though the screen works, it reacts to no touch input. I had already installed a new front display to no avail. I could not see any damage to the connector sockets either. I then removed the logic board, and then removed the tape around the display connectors. Under there I could see a lot of residue, possibly still causing shortcuts. I have then cleaned the board with 99% isoprop alcohol as described here: Electronics Water Damage But that didn't help, either. Still, the touch input is dead. I wonder if some of the electronics got fried on the board. The digitzer uses high voltage, right? I guess that (dirty) water would more likely cause a shortcut in such a case, correct? In this case, is there a way to replace those parts, likely a kind of power inverter? Or get them professionally replaced?

I just disassembled it and had little trouble putting the connectors back in. The large ones are easy and the two small ones can be pushed in with tweezers.