Anyone an expert on mobile LCD displays?
Apple is notorious for using "no-clean" flux in their contract manufacturing specs.  Thus moisture + corrosive flux residue= rust.  Consider it "toast" unless you can remove all the residue under Chips with solvent, vacuum and scrubbing. ( not easy) THey also use chemical moisture dots that turn blue for internal warranty void detection.

Better phones now have copper plating methods include moisture  resistance. such as I believe, Immersion gold over immersion nickel over copper and as such considered water proof to 1m depth with better flux cleaning bethods.