No sound from Sony STR-DE1075

I just received my "repaired" Sony receiver from Best Buy. I connected all of the cables as usual but when I finally powered the unit on, there was/is no sound.

I have used all of the troubleshooting tips included in the manual but nothing works. Can you help me understand what's happening?

Little bit more detail, I connected a DVD player to the receiver using an optical cable. The indicator lights on the front of the receiver displays that the 6.1 Audio is activated and kicking. However, no sound. Same with all of the other channels to include FM, AM and the CD player.

Hope this helps.