just like the power and everything else important in zombies tranzit, you will have to build pack a punch. first off you need to place a turbine infront of the door with the green and white lighting sign where the power room is loacted. after that is done you need to go to the bank vault in the last stop of tranzit, the burning city with jug in it, blow open the bank vault doors with grenades or any explosive, just one will do for each door, there are two. in the last room will be a lighting sing on a door, with the turbine placed infront of the other sign in the power room the door will be open and you can go into the basement of the bank and build pack a punch. hope this helps you.