I'm sorry to hear that you're having this issue.

Do you choose the 5.1 output option in either the game console, or on the DVD's title menu, where you can adjust the sound for 5.1 outputs? It seems strange that the test tones didn't give an indication if the sound was working.

I would recommend trying to choose a 5.1 audio selection in a disc menu and see if that helps. If not, it may be advisable to exchange the unit or have it repaired.