No sound output

I haven’t used my BB for 6 months. Tonight I plug it in using original power adaptor and the window looks normal and appears to operate normally , I can start and get the vertical bars counting across but I get no sound! I’ve used headphones, changed cables to my amp, tried both R & L holes, unplugged and restarted several times. Nothing seems to help and I cannot find how to do a factory reset. I press the Drum Set + Tempo buttons, scroll down to restore default settings and can get to the YES screen but can’t get any further. Any help would be appreciated.

Update the firmware if you have not already done so.

Check the volume controls.

Contact if You are still having issues.

I updated in May. Have checked volume knobs. Will try to update again.