Get a new battery and try it out. I repair phones as a hobby/job and I've gotten water damaged phones that work normally without any problems whatsoever. I even have put my own personal phone through the washing machine and it still powered up! It didn't work too well, but it was one when it went into the machine and I have no clue how long it stayed on under water but it still turned on after I let it dry out. If your phone was dropped in water for 5-10 seconds it shouldn't really be a problem. Just pull it out, take the battery out right away and let it dry. If you don't know how to take the phone apart, then let it dry out for atleast 4 or 5 days. If you know how to take it apart, then submerge all parts in alcohol minus the LCD for a few hours, then remove and let dry for another few hours and you will be good to go!