Is not mentioned, should take to dealer and hope for a big bill. You should remoive carb and clean fully the inside, remove plugs, squirt some shots of 50:1 fuel/oil mixture inside chambers, pull rope several times, hope that engine isn't already seized. That procedure should be done immediately OB was submerged and rescued.
Check if OB will start back again, if so run a full gallon of 25:1 mix to lube properly all rotaing components inside powerhead.
Happy Boating