battery does not charge - coconut battery says max charge is -1mAh!

I have replaced the battery on my macbook pro A1150 twice each time the battery works as normal for about a month before I get the "Not Charging" message. The computer works fine when plugged in - the magsafe light is usually dim green but occasionally bright green. Once unplugged the computer instantly dies. Magsafe works on other macbooks without issue, so don't think the problem lies there and not sure what the odds are of getting two new batteries both duds on delivery. I downloaded coconutbattery which displays the following settings:

Current charge: -1mAh

Max charge: -1mAh

Battery capacity: -1mAh

Design capacity: 5500mAh

30 cycles

power usage listed as 237.9 Watts

Since there don't seem to be any other issues I have narrowed my suspect list to bad logic board or bad left i/o board.

I have a genius bar appointment tomorrow, but my record at the genius bar is one genius out of every ten and don't really want to ship to Cupertino for a pricy repair. I'm pretty sure I can handle replacing any parts needed on my own but not sure where to start or what to look for if there's a short. Any advice appreciated.

Thanks!