The problem is not water and it is not drying. It is salt, and it keeps working while you wait.
People arrive here with a phone that went in the sea a fortnight ago and a reasonable belief that it dried out. It did. That was never the problem.
Sea water carries salt and a phone board carries copper, and where the two meet, copper turns into something that is no longer copper. That reaction does not stop when the water evaporates. The residue stays on the board, it draws moisture out of the air every night, and it goes on eating tracks and legs and pads for as long as it is there. Two weeks in a drawer is two weeks of quiet damage, and it does the most harm exactly where it matters, under the components too small to see.
So the first thing we do is wash the board, which surprises people who expected us to dry it. Every shield and connector comes off and the bare board goes into an ultrasonic bath, which drives the residue out from underneath components where no drying reaches. Then it is dried properly and it goes under the microscope, and the trail salt leaves is readable at forty times magnification: you can see where it crawled and how long it has been there.
Now the three things that make it worse, in order of how much harm they do.
Charging it. A live circuit with salt residue across it is a circuit being electroplated. It is the single most destructive thing anybody does, and almost everybody does it, usually four or five times over a week, because a phone that will not switch on is a phone you keep trying.
Switching it on to see. Same reason, smaller scale, and it is where the short circuits that finish a board tend to start.
Rice. Rice does nothing useful and costs you days. Days are the whole game.
Here are the numbers we see. Brought in on the day, off, uncharged: about three boards in four come back. Brought in after a fortnight of being charged to see: about one in five. That gap is not our skill and no technique closes it. It is time, and it is the only part of this you control.
One more thing, and it is the advice people ignore most. If your phone went in the sea and it is working perfectly now, bring it anyway. Washing a working board is a cheap, clean job that nearly always succeeds. Washing it three weeks later, after it has failed somewhere unrelated, is a different and much worse job.