New out of the box, the right headphone on my daughters QC35 ii headphones does not work. It works if plugged in but not on Bluetooth- nor with the setup assistant. I have updated it from the app but no change.
I'm sorry to hear that - what device are you trying to connect to Bluetooth with?
You've updated the firmware in the app so that shouldn't be the issue, but I would recommend performing a reset as shown HERE, then also to clear the pairing history of your headphones and devices as shown HERE. Let me know if this brings the audio back to the right earcup.