The connectors on the back of the board can very occasionally work loose. You can easily remove the board and reseat them though.
Follow the directions in the "Removing and Refitting your Bangalore Broadside Circuit Board" instructions which will guide you through making your Bangalore safe for working on and removing the board.
After first making your Bangalore safe to work on, remove the four screws holding the board in place, one in each corner.
Remove these screws (keep them somewhere safe).
Open the board up from left to right - keep the right hand side of the board in place and lift up the left hand side.
Look at the wires connecting into the board.
Bangalore Broadside Type A
If you have a Type A gun (Large Battery Version) there will be two green clips and two wires (Black and Red) that screw into the board.
Make sure the green clips are firmly connected to the board. Make sure the black and red wires are also firmly connected by giving them a gentle tug.
Bangalore Broadside Type B or Type C
If you have a Type B (Small Battery) or C (Solar Panel) gun, remove the board, as instructed above.
There will be three green clips on the back of the board. Check that the largest of the three clips (the one with the black and red wires) is connected properly to the back of the board and that the wires are secure in the clip properly.