So the younger family relative seems to break or otherwise render unusable her iPhone on a yearly basis, and begs replacement for Christmas gifts. It seems that people just don't understand the cost and value of something if they don't actually have to pay for it themselves. This time, it "fell in a puddle" and it was several days before brought to me, the family electronics repair department. I popped it open and got as much water out as possible. After that, left it in a bag of rice for a week. It powers up, but has trouble charging and isn't recognized by computer USB connection except sporadically. Took it back apart and left it inside the data center (very cold and low humidity) for another couple of weeks. Finally it seems dried out but there are splotches on the inside of the glass between glass and display where you can't get it apart. USB somewhat better but still flaky. My last attempt has been to soak the thing in isopropyl alcohol then leaving it to evaporate for the next week. Assuming this doesn't help at all, what to try next?
Buy a new iPhone After that long drying it out, I doubt there's much else you can do Buy a new screen maybe
Wait for a month and get a new iPhone 6. I also don't think you can do anything better for it. You almost did the best ever human can do on such this case.
put it in a container full of rice, just leave in there for a month. when you take it out, it will be a Mitsubishi seriously though, container of rice helps, that sucks the moisture out of everything.
teach her those values you talked about and get a basic phone for the next year or two. or switch her to straight talk and get the $30 LG smart phone that can be replaced at a much cheaper cost.