How do you fix a phone with water damage?

If you have a laundry dryer with a drying rack (a rack that attaches within the the dryer drum in a static position... designed for air drying of sweaters, shoes, etc.) place it in the dryer, on the rack, on the lowest heat setting possible (no heat, air dry or fluff) and run the dyer on the longest time setting that you have. This is not a science, but it saved my iphone (where the battery cannot be removed) to full recovery.

You may not be able to. Remove the battery and try to dry it out by putting it in a jar of uncooked rice for a day. It will help draw out the moisture.