Water damage, still works but dim

[Guest chet255]

Hey, I have an pmx220 and a friend of mine sent it swimming in the toilet. The phone would not turn on and I put it away thinking it was totally done, but I found it the other day, plugged it in and it worked! The problem is the screen is really dim to the point where it is hard to see. Sometimes though if I bang it it will return to full brightness. Would a new battery fix this, if not will anything? Please let me know.