sounds like the car has some kind of ignition immobiliser on it and its not letting you bypass it, ask your bro if there is a particular sequence you have to follow in order to dissarm the immobiliser, or failing that consult the owners manual to see if there is a procedure that must be followed after a battery replacement / power disconnection. I own a 318se and have never come across this problem which makes me wonder if some form of after market ignition bypass device has been fitted to the car, perhaps one of the other members will have a better idea than me.