[Alan Anderson]

Clicking usually means that something is drawing enough current to trip a circuit breaker. The breakers are auto-resetting, so the clicks will repeat rapidly. (You mentioned a "bad" Jaguar? The typical cause of that would be connecting power to the motor output instead of the power input.)

Buzzing would be coming from one or more of the boost power supplies providing up-regulated 12 and 24 volts. If the battery voltage drops low enough, they can get noisy. I've also heard a squeal at a very high pitch when I used a 12-to-5 volt converter other than the one from the Kit of Parts.