[NoiSeeVT]

Looking at videos and everthing else it seems to be internal. The amp just is not repsonding right. The only thing that is wrong is the way the you bridged the conncection, is it a 4/3/2/1 channel amp or 4/3/2.

Still when you have touched the gain it goes red again sounds like something inside. Do you have someone close by with an amp you can try. This would be a good way to test your wiring, if it sends another amp in protect something is wrong with the output from the deck, if not then you know the amp is the problem.
David