Wet iPhone 6?

My son's iPhone6 was in an Otterbox but still got a little wet. The side buttons (volume) seem to not be working, and the "Ringer" icon won't come off the screen. Will putting it in a bag of rice overnight help? I've heard that the "rice trick" doesn't work. I'm worried for the kid, he does take good care of it and I'd hate to see it ruined. Any other ideas to help get it to work properly again?

Thanks in advance for your advice and/or tips!!!