Although it sounds extreme, if your electronic device gets salt water in it IMMEDIATELY removing the battery and thoroughly flushing it with multiple distilled water baths followed by proper drying may save it. But the battery must be taken out immediately and the salt flushed before it does it corrosive damage.
Whether this works largely depends upon whether you got the battery out before bad things happened. And of course proper drying must be done after the salt/mineral residue is flushed.
If the damage was due to fresh water this extreme intervention should not be followed.
Note that most tap water along with most bottled water has quite a bit of mineral content and flushing with this stuff may do almost as much harm as the original incident.
For isolated water exposure WD-40 was originally developed as a water displacer for firearms and other outside use items and it does this very well. But this formulation of light distillates of petroleum on a sensor or inside a lens would be very difficult to remove so it isn't something to be used indiscrimately but works well on circuit boards and in switches or controls to displace fresh, not salt, water before it causes damage. Any salt must be flushed with distilled water before trying to displace or dry.
Alcohol will combine with water but except for the very pure types will leave its own residue signature behind when if finally evaporates; alcohol is generally OK to clean electronic components but it will attack many types of seals and other components which is one of the reasons ethanol laced gas creates problems with vintage vehicles.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
