I find it hard to believe the empeg could have fried another head unit; head units (and the empeg itself) are protected against almost everything as car electrics do nasty things (like -100 volt pulses, etc). Your empeg acting totally dead is a symptom of the ground fuse (non-resettable unlike the power fuse) blowing - we just fix this and all will be well.

Check the fuse in the other head unit's wiring harness, in the car fusebox (there's usually a separate feed for the radio), and check the ground wire going to the radio is *really* ground. I can't tell until I look at your empeg, but the loose wire may have put a lot of current through ground/power and blown a fuse somewhere.

Let me know how you get on. I suspect it's something simple like a fuse, but in the worst case we might be able to get our loom manufacturers to accept liability.

Hugo