lol, i cant believe some of the advice here.
ok for one, if its not working at ALL, then it has nothing to do with wire gauges, alt or fuse sizes. Jesus use your brain. Even if that stuff was too small it would still play slightly. Obviously your battery is charged if your starting your car. OBVIOUSLY the deck, rca's and speakers are working fine if you put your old amp on and it works. Even if your gain was completely wrong when you turn your headunit all the way up it would vibrate or SOMETHING.
Clearly its an issue with your amp. Maybe a blown fuse on the amp? If its coming on and still no output, it could be a mechanical breakdown. Maybe the amp is just fubared. At that point your going to want to send the amp to someone who knows wtf they are doing with amps. Return it or something.