I recently did a reinstall.upgrade to mar car and now my subs aren't playing. I swapped out a twochannel amp for a four. I ran a new rca from my processor to the four channel amp for the rears. I changed nothing about the sub amp in the install. Now when I turn on the system, the cap comes on, then the two amp light up and nothing comes out of the subs, no turn on noise, nothing. WHat could be wrong and what should I do