iPod with water damage & white screen with no sound isues.

I know there are lots of water damage issues already, but my situation is specific.

The iPod was outside over night, in the cold wetness of a friend's driveway. At first it wouldn't even power on, but after a few weeks of sitting in rice, I've got it going. The sound works fine, and the screen is even registering my touch, but the white screen wont go away, although it has improved over time. Before it was streaky and I could see the water and bubbles inside it. Now there's only a small patch of pixelated streaks, and the corners are tinted yellow.

I'd like to know exactly what's wrong with it so I can have it repaired instead of buying a new iPod.