Have you double-checked your power connections, slowly and carefully? Something doesn't seem right on the board. I would expect to see a red wire for the positive supply, a black wire for the negative supply, and (whatever) for the ground connection. I haven't traced everything; it's just that the supply wiring seems a little odd.
When you're quite sure it's perfect, put your voltmeter on the connections and the board, and confirm. If you would like, you can do that without the rest of the circuit connected, so all you are verifying is the supply connections.
And just a comment... I would have expected "master" to be used for the positive supply, not because it really matters, but because it seems more conventional to control things from the positive side. Usually.