No, I never tested it in another car, I tested another amp in my car and it did same thing..
I can test it in my sister's car if i get the chance to. Thats if your interested.
I mean this amp looks in perfect shape i just have no idea why its tripp'n
I tested it on a battery (not hooked up to a car) and the green light comes on then it changes to red. When hooked up to my car, it goes straight to red.
There could just be some tweaking to do or something i'm not certain. But I'm selling all my car audio stuff (no more for this car, maybe the next car)