amp problem i can't solve.

well, i blew the first head in my wonderful little nissan stanza, so i had to replace it with unit that came in it, a low end, kinda old, german, pioneer. its a good head unit, but the freak who owned thsi think before changed the wiring all around and generally screwed it up, so i have spent more than one weekend with my head in the dash splicing bare wire to bare wire so i can plug in a head unit.
but i'm angry and rambling.

the short story is that i got it all hooked up again, and then plugged in my amp/sub system. everything on the amp is the same, except that the remote power and rca's come from a new unit. but now, it seems like i get no push at all from the sub, and i can't put the volume up above half or the amp cuts out on the low beats. it doesn't go into safety or blow a fuse, it just blinks, right in time with the beat (kinda cool looking anyway. i started fixing the grounds, checking them out, and it seemed like it helped, but it is still very weak. my 200 watt amp used to be able to shake my car satisfactorily, but now i have to touch the sub cone to see if its on at all.

any ideas? i'll keep this site up and recieve any pm's. i want to fix this soon.

i have been reading other forums and it seems like one of them said my battery being low might cause this problem. is this possible? how do i recharge my battery?

Bring the battery up to the service dep. at Walmart or a place like Autozone. Or just buy a new one.