Another MSD 6AL Problem

[rms427]

Just got my car back from the shop and it lasted about 5 miles. When the engine builder hooked the msd up as it should with the orange wire to the positive and the black to the negative coil terminal the car wouldn't start. He then hooked up the white wire to the negative coil terminal and it ran fine but the tach was eratic. In the mechanics defence both wires actually black at the point where they are near the coil. I had just changed to a magnetic pickup distributor and had not cut off the white (black) wire. I drove the car about 5 miles it started to miss and then died. Now it won't run at all. I have hooked it back up the way it should be and it still doesn't work. I tried shorting the magnetic pickup and all I get is a sound at the 6al box but no spark. I have tried to coils. My question is why wouldn't it run when it was hooked up properly in the first place and yet it ran for a while with the white wire hooked up. I assume something is now shorted out. I wouldn't think it should have run at all with the white wire hooked up to the negative coil terminal. Could it been caused by an internal short in the MSD 6al box?

Thanks,