No Audio from MX-1

[Sunluvva]

Hi, I recently bought an MX-1 second hand, in box, unmarked, all case candy present. Got it home, no sound.

I did a factory reset and checked the OS is current (1.05). Plugged in external Audio gear (2 synths, an MPC, an electron model samples and a TD-3) checked all cables, nothing. Headphones, stereo outs, and level meter do not register at all. I don't have any AIRA gear so havent tried the USB ports, only the Audio ins. My Mac (M1 chip, Ventura 13.4) can see it but when I select it as an output device theres still no sound.

Ive got all the knobs maxed (except the mixing knob which I've swung back and forth), tried with the Mastering button lit and unlit- zip.

If I cant work anything out I'll take it to a repairer to check for a dead amplifier board / ADAC (if that's a thing). Aside from that, is there anything else anyone can recommend I try? Thanks in advance :)