2005 Volvo V70

I have a volvo V70R 2005. The radio HU850 will not work. If the car is running for a long time (45min) It will sometimes work but only on channel 3 and only through the front speaker. The channel display is always working but no sound (no output) The dealer told me it needed a new amplifier booster which is located under the passenger seat. I replaced this with a used booster but it did not fix the problem. Do I need a new radio itself or is it more likely the amplifier booster I put in was also bad?

Usually when you install a new control unit you need to download software to it. So if you put a used amplifier then it is not compatible with your vehicle since software can not be downloaded to a used control unit and you can not configure it to your vehicle?

May 25, 2011.