welovesnow, the first thing I would suggest is that you clean your phone. The rice is a great first step, but it will not fix your phone, nor will it prevent corrosion damage which might occur later on. Use this guide to clean your phone. It was written for a 3G but it will still pertain to your phone as well. The repair guides for your phone are here. After that you want to check this "There is really no a surefire way to say which part is the one that gives you the problem. I would recommend that you start it systematically. Clean the dock connector, make sure there are no broken, bend or corroded pins. If after that you still have the same problem, replace it. Re-evalaute for any further damage. Oh yes, one more thing, make sure that you have the right USB cable. I accidentally used a wrong one, and got the same error :-) Anyway, hope this helps, good luck.