The device needs to be properly treated for liquid damage. I strongly recommend powering it down and leaving it off until you address this condition. Do not rely on rice to take care of this! You can find a technique guide [guide|5825|here]. Go to the iPhone 5s device page also and review the teardown before you attempt to do anything so that you can be better informed as to whether or not this is something you are comfortable tackling. A word of advice: if you do choose to disassemble your device, be very careful of the ribbon cable for the Touch ID sensor.
Good luck to you!
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