There is a test that we can do that will tell us what is going on with your subwoofer. The green light is only going to tell us that the electronics in the sub are active.
I would connect a CD or DVD player directly to the sub, using both left and right analog RCA inputs. We don't want to include the receiver in this operation, just the sub and the source player. Put a CD in and play it.
If the sub is going to work, this is where it will happen. If the sub still does not play then we have a problem, and will more than likely need to replace the amplifier.