The 5S can be tricky if you don't keep track of the screws. On the Screen Bracket, they are all of different sizes and differing only by 0.1 mm. So if you put a longer one in the wrong place, you can certainly cause some major problems. Do a search on Long Screw Damage to learn more.
You also need to disconnect the battery before disconnecting the screen otherwise you can blow the backlight circuit. However, your problem is touch related. I would carefully [guide|30962|remove the screen] (see my note on the battery above) and visually inspect the connectors for debris, damage or missing components in the surrounding area. Then re-assemble and test.
Then get back to us with more details and we can guide you from there.