If you've installed another amp in the same setup and it works, sounds like the amp in pouched and you need to get a new amp. Electronics have a lifespan......... or an abuse-span ...... LMAO !!
Current : 2013 Mini Countryman JCW, 2007 Z4M Roadster
Past: '88 E30 M3, '69 BMW 2002 Ti, 2000 328i, Audi A6 TT, BMW X5 3.0i , Audi A4, Mini Cooper Clubman S 1.8T