New Yamaha RX-A4A receiver - right surround channel not working

Just picked up this receiver on the latest Amazon deal, and it looks like it might be defective. Not the most impressive delivery - it was contained within a much larger box with no padding, and delivered on its side with the outer box’s tape half-open. The Yamaha box looked fine, and everything looked pristine within it upon unboxing.

After basic setup setup (in a 5.0.2 bi-amp configuration) I noticed to my chagrin that the right surround channel was silent when running test tones. To eliminate issues with that speaker or its cable from the equation, I connected it to the left surround channel and it produced a test tone.

Is there anythjng else I should check before boxing this beast back up and rolling the dice again?

Thanks in advance!