I had the same problem: Nokia 7 Plus, dropped into the toilet, the phone seemed to work except the touch screen did not respond to touch. I took it to a trustworthy repair shop (Fonum in Finland), and they had a look at it and said that it couldn’t be fixed. However, my father-in-law insisted that if we soak it in isopropyl alcohol it would work (I think the idea is that isopropyl alcohol replaces the water, and eventually evaporates). As we didn’t have anything to lose we tried it out and it actually worked: the screen is now responding to touch, and the phone seems to work perfectly. The only downside is that the screen is now kind of messed up — looks like there are small amounts of liquid under the screen, and some other discoloring in parts of the screen — but I guess we could now replace it. Thus, if you really need to get your phone working and nothing else works try to soak it in isopropyl alcohol. It will mess up your screen but it might make it responsive again. Note that we did this ~2 weeks...