Take the back off the phone.
Take a portable hair dryer and put it on warm.
NOT HOT.
Let the hair dryer blow warm air across the RF shields
and logic board and all the iphone guts for like....a day
or two. It's the hours-n-hours of blowing warm air across
the parts that dries it out thoroughly. The rice trick is good
but it doesn't drive out any moisture. Rice will only absorb
moisture that happens to evaporate into the surrounding air.
Liquids in small spaces may not evaporate easily without
forced blown air.