I recommend that you pull the battery and leave it open all apart.
Put the phone into a 2.5 gallon bag of white rice.... a smaller bag will do, but the larger the better.
Leave it in there for a minimum of 24 hours, 2 days is better.
that will suck the water vapor out of the phone's innards.
the touch buttons should resume working again AFTER all of the water vapor is gone.
IF, you have access to a vacuum pump.... see Harbor Freight, they are cheap.....
Take a gallon jug, jar, with a tight cap on it, metal cap is best.... whatever, insert a nipple and make sure it is tight, use cement, rubber glue, etc......
run a hose from that nipple to the vaccum pump.... pump it down to -26 inches of vacuum on the gauge.
Keep it there for a minimum of 1 hour, 2 or 3 hours is way better..... all of the water vapor will be gone.
If the phone is going to work, it definitely will work again with this treatment.