bushing is a bit too pessimistic, I think.
I managed to drop my iPod Classic into salt-water. It also went black, and I did some of the don't's in the immediate panic.
However, after letting it dry there was some reaction (even though still malfunctioning).
I ended up changing the battery (which might not have been necessary) and cleaning the logic board with some poissinoius chemical using a soft brush. And after having targetet the battery connector and the part of the logicboard around it several times, my iPod is back in order.
So I suggest taking it apart and cleaning it with a suitable product (the iPod ought to be dry by now) to remove corrosion. That might result in some sign of life and possibily a diagnosis with a better prognosis.