Best thing to do with any electronics that fell into water is :
1 - take out the battery (or any other power source)
2 - take out the cars (SD, SIM, ...)
3 - take it apart as much as possible without tools
4 - put it in a bowl of rice (dry rice), make sure the rice covers the electronic completely and leave it there at least a few hours (1 day would be probably best).
Also, you could use a plastic box that can be sealed (usually used for food storage).
I know many would think it's stupid to use rice, but it's very absorbent and it's something you can find easily around the house (or at least in the kitchen
I had an old phone fall into water and put it in rice and the phone still works (after about 4 years after the accident), too bad i don't have a use for it anymore (it was a "dumb phone", you know, the "brick" type).
P.S. if after drying it with rice it's still not working, check if the battery/accumulator is good (it might have gotten "fried" when it fell in the water, the short-circuit can destroy completely a battery/accumulator), if the battery is good but the device still doesn't work, best thing is to take it to a repair center.