Here begins the cleaning! You will need the highest concentration Isopropyl Alcohol (Rubbing Alcohol) you can get. Don't settle with anything less than 90%. Why? Well, if it isn't rubbing alcohol, then its water. Water is conductive and can hurt your phone. Rubbing alcohol will remove corrosion and will not hurt your phone.
Scan the phone for any water or corrosion. We will later use the rubbing alcohol to 1) Displace the water. 2) Remove the corrosion.