[nixnexus424]

Did you replace the head unit?

On your radio wiring harness, there should be a blue wire that powers on the bose amp. Check to see if there is 12V running through. If not, check the fuses. you have to make sure the wire that runs to the rear bose amp is seeing the 12V, either by using the 12V signal from the radio or tapping from the fuse block

to run input to the amp, you either need a new head unit with pre-amp outputs or use a Hi to Lo convertor, then run off the rear speakers.

i don't think the new amp will work if you tried wiring the speakers' output straight to the new amp's input without the Hi to lo converter. if it did, it must have been really distorted at the default gain level...