I'd say check the fluid level, check the connectors, and also check the mode selector. Maybe when it sank it pulled something down to much and messed up the mode switch somehow??? That's all attached to your shift selector and maybe the mode switch cracked or broke or something?

When was the last time you checked/changed the fluid and filter? Might be a good time to do that. Who knows, maybe the tranny issue is just a coincidence.

Bart