HELP - Mackie Onyx 12 No Audio on Main or Phone?

[RogueWarrior]

Hello all, I am new here. I have some Mackie Onyx 820 and 1220i mixers in my home studio, but my main 1220i was damaged during some recent repeated power outages (switching power on, the lights light, then shut off repeatedly) so I assume cooked PS.

I picked up a 2nd hand Onyx 12. Appears brand new but was 'open box'.
Got everything hooked up and, set the clock, adjusted input faders and set levels to unity / 12-O'clock, connected some inputs including USB driver to my DAW, depressed LR button, everything's unmuted.

Problem is the main meter do not show any audio level. If I Solo an input, then I get main meter level to show, but no matter what I've tried I am not getting ANY OUTPUT On Main (XLR) or Phone ports?

Any help greatly appreciated - TYIA.