Hi mickf,
Have you powered off, waited a few minutes and powered on again?
Do the speaker connecting cables have metal bodied plugs - these could be touching and shorting the outputs - try slipping a piece of card or thin [plastic between each of the plugs to isolate them.
If it's not that - do you have anything plugged into the 'Line Out' socket on the B2?
If you have any headphones or ear buds try plugging those into Line Out, turn the volume up to 50+ (to get a reasonable level) and check if you can hear any sound from there.
Have you toggled 'Audio on HDMI (TV)' on and off a couple of times to makes sure the command has got through to the B2?
Paul
Brennan Support.