first check the wires with the volt meter. make sure you have 12v on the power and acc lead (when the key is in the 'on' position) check your ground using the resistance setting on the voltmeter. you should have 0 ohms for resistance. try hooking up the computer to an regular computer psu that you plug into the wall outlet, make sure that the computer is working and not the problem. if all those things check out, then it may be a problem with your power supply.