Diagnosing an electrical problem

I put a new alternator in and tried to jump start it and nothing at all works not even the interior lights. I just bought a new battery less than a month ago, but I had died cause my lights were left on for a long time. The first time I got it jump started there was a little bit of power going to it but it would not start. So I got it towed back to my yard and put a new alternator in it and tried to jump it again and that time nothing had happened at all. There was zero power going to the car.