Demo while playing from a flash drive

Hello. I have the Denon MCX8000 and I was inconvenience at my last play. I played from flash drives and suddenly a demonstration demo took place on my left deck. I do not know whether I made it by a combination of buttons, or it was a software fault. Do you have any experience with it? Or, how can I cancel the demo without having to reboot the entire device? Thank you.

The only way to invoke “vegas mode” is to power the unit up whilst pressing the vinyl button. Never heard of this happening during a set.

I did not touch the power buttons. Still, nothing happened after 2 hours of playing.