4x4Pathfinder202

Hi all, i have a 02 pathfinder with bose 6 disc cd changer. I was just wondering if there is anyway to install the 05 and up bose 6 disc cd changer in my 02. I bought the 05 radio off of ebay, plugged it in but there is no sound. The radio turns on and cds play, just no sound. I read on other forums that it is just plug and play. Another question is if the 05 radio works in my 02 how do I hook the steering wheel controls up? Is there a adapter that would make this work? Because the 02 connector is round and 05 connector is rectangle. Please if anyone has info on what I can do then please reply. Thanks