I removed the stock radio because it won't power up. There is a black in line box which houses a circuit board. It has a yellow, pink, and blue wire coming in and then the same color wires going out to the radio. What does this do?

Also, power is coming in to the radio through the red wire but the radio itself will not power up. I'm guessing this means the head unit is dead but I really hate to go away from stock because it will also disable the cd changer. Are there any other head units that will operate the cd player in case I have to replace? I know it is an alpine cd player so I was wondering if an old alpine unit would work

 

This is a pic of what I'm talking about. Does anyone know what that is?

 

It would help to know what car you have. I assume its an XJS? If so, what year?

Mark