NekoMichi

Try opening the iPod up and checking the LCD connections. Maybe part of it is loose and not properly connected. Also make sure the metal contacts are clean and don't have any finger-grease on them. If this doesn't work, then there is a chance that you accidentally damaged the wiring inside the LCD ribbon, in which case, the LCD has to be replaced. Make sure you don't put pressure or get scratches on any ribbons as they are very delicate and break easily. Damaged ribbons aren't physically obvious to spot until you turn your device on.

In the best case scenario, you have a non-original or faulty battery and your iPhone is rejecting it. (hope this is the case) In the worst case scenario, the water has corroded the terminals on the battery connector of the logic board. In which case, you should either get the battery connector repaired or even replace the entire logic board. (expensive) Your best bet is to try using the battery you just ordered and see how things work out. Hopefully it's just the battery that's problematic.

Well, it doesn't look like there are many problems with this iPhone other than the bad LCD (not too difficult to replace). Try making a few test calls and just generally test it and see if any problems arise through normal everyday use. If you have the iPhone configuration utility on your computer, try plugging your iPhone in and reading the console log. This can sometimes tell you about errors that you wouldn't otherwise physically see on your device.