My wife's iphone accidentally made it into the washing machine for a full wash cycle. After extensively drying it, it would only turn on when connected to wall power, and the battery would not hold a charge. I was hoping the lithium battery was just shorted past its minimum voltage. Since the phone did turn on, maybe I would get lucky and that would be the only problem.
Repair went pretty smooth. Removed a few extra parts past removing the battery to make sure things were dry. Upon removing some of the connectors, there were whitish marks around some of the connector edges. It looked like corrosion or... burn marks. Well, time to find out. I put everything back together with a new battery and the phone turned on without wall power. It was not able to find a connection to the mobile network (just showed "Searching..." in the top right corner). Also the touch display was flaky in responding and the phone would reset every so often. So I think the white marks burn marks where the battery shorted. I think the shorts also caused other damage on the main board which lead me to the decision to not spend any more money on parts since there is a good chance most of the damage is on the main board itself. Iphone 5 may be release within the next couple of weeks and we are eligible for new phones so I think It will ultimately be cheaper to buy a new one.
Downside to iphone is that you can't easily remove the battery. When you are in a situation where the phone gets wet, removing the battery before a short can occur can save your phone. In this particular case any phone probably would have been dust since it was in the whole wash cycle, but it did make me realize that there are times where removing a phone battery fast enough can save the phone. The built in iphone battery makes this impossible to do.
On a positive note I found the Magnetic Project Mat invaluable. I tore apart the iphone almost completely and there are so many little screws of different sizes that it would be really hard to keep track of what went where. Placing parts from each step in the different sections of the mat made putting it back together possible. I definitely recommend the magnetic mat if you take small things apart from time to time.