In California, the lemon law criteria is pretty straight forward and you don't really need a lawyer. BMWNA understands the California lemon law. You should read (Google) the law yourself since California has put it in an easy read format.
You need to get the service manager on your side. You need to call BMWNA and state your grievances and have them get the ball rolling by contacting the service manager.
You wont get all your money back even if your situation meets the lemon criteria. That's because you used the car. There is going to be a depreciation factor based on mileage which will affect how much you get back. I'm pretty sure this is the case even under California law.