2004 acura tsx radio

  my friend has a 2004 acura tsx with factory 6 disc in dash changer.  the radio stays on, so the dealer had unplugged it to prevent the battery from draining.  apparantly this is quite common for this radio.  a repair center wants $185 to fix  it.      has anyone put an aftermarket head unit in this car?  i found a harness that fits, but havent seen a mounting kit anywhere.  however, there is a sweet spot i could make one out of abs and stick where the pocket goes under the radio.          my real problem now is that i think there is an amp somewhere in the car.   i tried to "pop" the speakers using a 9 volt battery and got nothing.  usually that indicates an amp.  i even tried to power up the antenna wire off the harness.  please advise on wiring, or location of amp.  ide prefer to not have to run wires to all speakers.    thanks.