iPhone 4s not charging, low input voltage

I've had an issue for a while with my iPhone 4s where it will not charge. A while back I had replaced the battery, and it was perfectly fine. Soon after, it stopped charging. I replaced the dock connector twice, and it still wasn't accepting a charge.

I finally looked around yesterday to try and find out voltage specs to measure if the phone is getting power, and I discovered that the battery connector is only getting about 0.8 V when the phone is plugged in (with the battery out, of course).

I tested for voltage at each pin on the battery connector. The bottom pin showed nothing, as it is a ground, but on the second pin from the bottom I got .01 V, third pin I got .02 V, and the top pin I got 0.82 V.

So, my question is how do I fix this? I read something about a USB charging IC, but nothing was very clear on how to replace it or anything about it, really. Is there anything I can do to fix this? I would like to get the device turned on.

From the schematic I found, I don't quite understand where the capacitors are that I should be testing. I tested the capacitor circled in this picture, and it started around 20k ohms and stopped at 70k ohms. From what I have read, the charger IC is that black square next to that capacitor.

I did not mention it before, but as you can see from the water damage sensor, this phone has been in water before. This was at least 6 months before any charging problem was present, though, and the phone worked perfectly up until it stopped charging.