I think rice is the way to go. The only other way you could get all the water out of it quickly would be to take it apart (which only a technician could do) or to put it someplace really warm (but not so hot that it would melt any of the plastic).
Make sure the battery is out of the phone and the battery cover is off, but put the battery in the rice too.
Try the rice for a couple of days, then try it. If it's still not working, do a couple more days of rice. But it may be too late no matter what. Good luck!