When I get back ill give you a hand a see if we can't get your battery issue sorted out. I have a feeling your battery is just dead which is the least invasive and most easily fixed issue
. Hasnt it been sitting for a bit after you bought it? that may have led to it being bad... Before then, take a look at your ground straps, terminal connections and everything else these guys recommended.
How's the rest of the car going? When you clean it up take some pix I'm sure threes guys would be happy to see another e30 around