The only way to possibly get your phone working properly again is to clean it properly, by dis-assembling it and using IPA 99%+ to clean all the affected parts as outlined below
The impurities in the water causes corrosion and provides circuit paths for the electricity which were not in the phone's operating design and could damage the components.
Rice does nothing to fix the problems caused by corrosion Don't Put Your Device in Rice. Here's Why
First do not try to charge or to turn on your phone and then remove the battery as soon as possible from the phone to minimize further damage.
Then you need to dis-assemble the rest of the phone and clean all the affected parts using Isopropyl Alcohol 99%+ (available at electronics parts stores) to remove all traces of corrosion and water. Do not use "rubbing alcohol" as in some cases this is <70% IPA, can contain additives and is not as effective. If you do check the label to verify the amount of IPA
Here is a link that describes the process. Electronics Water Damage
As always with electronics, especially surface mounted pcb be gentle when handling and especially when brushing away the corrosion. You do not want to remove any components from the board.
Hopefully after you have done all this the phone might possibly work correctly again.
Here is a link to the ifixit guide(s) for repairing your phone, which may be of some help to you.
Samsung Galaxy S5 Sport Repair
If this process seems too daunting, take your phone to a reputable, professional phone repair service experienced in water damage repair and ask for a quote for a repair. If you decide to do this, do it sooner than later.