I feel for you (after my son flushed a damn good phone down the toilet).
As has been said above, take it apart, put it somewhere dry. I would of done this, if it hadn't been flushed away
If you try it & it doesn't work, you haven't lost anything. If it does work, you don't need to buy a new phone
When things are sold as "water proof" I generally take that to mean "water resistant" (and that means its only a matter of time).