If, when the Bangalore tries to fire, you can hear the gas injecting but it doesn't ignite, it could simply be that the battery has insufficient charge. This is especially true if you can hear the gas injecting but can't hear the rapid clicks of the spark plug.
A battery can discharge quite a lot and still provide sufficient power to run the control box. However, to ignite the gas, the battery really needs a much higher charge.
See "How much charge is left in my battery?" for more information.