Where i need to ground my audio amplifier to if my dry cell battery is grounded to the car body?

i have a 2 awg power wire running from the front battery to the dry cell battery in the trunk. The dry cell battery in the back is grounded to the body of the car? i had the power wire from the dry cell battery in back going to my amplifier as well as the ground from the amplifier going to the battery but the red light on the amp comes on even though the emblem on the amp lights up is it not grounded right? are the rca plug ins not right from the cd player i have the plugged into line in on the amplifier? i have an 80 amp cylindrical fuse holder from the front battery going to the back and a 150 amp flat fuse block before the power wire in back hits the dry cell battery? could someone possibly help me out my set up is supposed to be for up to 2600 watts and i bought a new amplifier thinking my amplifier was bad but their is no way a freshly opened amplifier could be bad?