Why won't my screen work?

Hello. Long story short, my Samsung Galaxy s4 mini was drowned in salt water. It was in uncooked rice for about a month. Now when I turn it on, everything is normal and looks just the same. Except that I have a dotted password (you must draw your password with the dots), and the middle half of my screen doesn't work when I press it, and the two side buttons don't light up. Any suggestions on how to fix this? Thanks