galaxy s4 back button not working properly

[barha ch]

hey i wanted to say that i dropped my phone in water for about 5 secs and then it was turned on and i tried to dry it immediately but connected to a charger for a few seconds to check but then turned it off and dried it for like a day then turned it on and check everything was ok apart from the back and options button it kinda works but then stops working and then i have to lock it, then it works again ... i dried it for another day still the same problem

 

[Nurocyon]

If you drop any electronic device in the water, it should be turn of immediately, remove battery and let the device dry 3 - 4 days covered in rice before turning on again. Because you connected your phone to a charger, it might be now damaged permanently.

Sent from SGS4 (GT-I9505)

 

[barha ch]

If you drop any electronic device in the water, it should be turn of immediately, remove battery and let the device dry 3 - 4 days covered in rice before turning on again. Because you connected your phone to a charger, it might be now damaged permanently.

Sent from SGS4 (GT-I9505)

Yeah the back button is still not working.. so should I send it to the samsung factory to repair it? How much will it cost approximately?