Is there anyway to fix 'water damage'

David, I strongly recommend that you start off by cleaning your phone. Disassemble your phone using by following this guide. Clean it using this guide. It was written for a 3G but most certainly still applies. Make sure that you clean all connectors and cable ends and the dock connector as well. Check for corrosion across the whole board, remove the EMI shields. Check for missing or burned looking components. It may require more than just one cleaning cycle. Once it is cleaned, replace the battery. Reassemble your phone and re-evaluate. Without cleaning it, any answer will only be a guess since this can be caused be corrosion failure of SMD components on the board as well It may have been shorted out. Hope this helps, good luck