Installed a new battery having problems...

I've had the unit installed into my 2000 GTI VR6 (which comes with the Monsoon system). I've had it installed for over a month now. It worked fine but yesterday my battery died and I've replaced it. Since replacing it I get power to the empeg but no sound comes out the speakers when it plays.

In the installation I had them remove my head unit and I only have the empeg in there now.

I'm no car audio expert and I'm not sure if putting in the code (that comes with the Monsoon system) turns on the head unit or the amp. If it turns on the amp I'm guessing this would power on my system properly. The other problem is, if I have to put a code in, how will I be able to do this properly without my head unit?

Anyone have any suggestions?

Maybe it's just a blown fuse someplace?

Thanx I'll check them today, totally forgot about the fuses, duh.

AFAIK, only the HU is code-locked to help deter theft. My money's also on the fuses.