HELP...Headunit problem?

I have a pioneer DXT-2266UB headunit with 2 10" MTX subs on a 500 watt sony xplode amp. Everything was working fine until recently. one day i turned it on and the subs werent hitting. i popped the trunk and it seemed that the subs were playing music but barely any bass and a low volume. when i turn up the volume on my headunit, it doesnt seem as if the speakers are getting enough power.i have pulled everything out and checked the wiring and it all seems to be fine. i have checked the pass filter and thats not it. i checked the power cables and they seem tight, however the ground wire seemed to have coroded a way some, leaving a strange white dust, so any ideas?

possibly either

-fuse on powercord

-or need new ground wire?