A phone that has been in sea water does not have a water problem. It has a salt problem, and salt goes on eating copper long after the phone feels dry.
That is the whole reason the first thing we do is wash the board rather than dry it. An ultrasonic bath lifts the residue out from under components where no amount of drying will reach, and then the board is dried properly and looked at.
The number that matters is days. A phone brought to us on the day it went in has perhaps three chances in four. The same phone a fortnight later, having been left in rice and charged a few times to see whether it would come on, has perhaps one in five. Nothing we do closes that gap, so the best repair we can offer most people is the sentence bring it today.
And the three things not to do: do not charge it, do not switch it on to see, do not put it in rice. Each one takes a board that was repairable and puts corrosion across a live circuit.