power supply. disconnect the 20-pin connector near the top of that picture to the left of the fan, and plug in the normal pc power supply there. then you just need to short the power button pins on the board. anything from a old computer power button to a butter knife will work for this.
this method does not test the dc-dc power supply, but that is easy enough to test within the car. the power supply is fused, and any wires you run to it should be fused, so a fire should not happen unless you bypassed the fuses or used too large of a rating. i believe the m2 has a 15A fuse on-board, so as close to that as you can find on your battery fuse would be best.
those are GLI's, or Ground Loop Isolator, and i only recommend them only after you have issues with rpm whine, or constant whine in the audio signal. if you don't have any issues like these, these are a unnecessary layer to fix a problem that doesn't exist-- hence why i only recommend messing with them only after you have the problem..
i can never remember if it is the red or the white that is the trigger wire, but i know that both are positive wires. one requires a constant +12v, the other is the trigger wire to turn it on- the acc wire like on a aftermarket amp.
the black wire is your ground.
to test it off a car battery, just connect the red and white to the positive terminal, and the black to the negative terminal.