DJM-750 switching off and on randomly

I've had a DJM-750mk2 for around 8 months now I upgraded from My DJM-450mk2. It has worked perfectly until recently where it has started to switch off while mixing or just playing music and powers straight back on again. It's extremely random and have video footage of it doing it on different occasions. I have sent it back twice to a dedicated pioneer dealer to repair but they can't seem to replicate it happening I literally got it back last Thursday and mixed last weekend for 4hrs and it worked like a dream. Used it throughout the week and the same worked perfect but tonight I was mixing for about 30mins and it powers off and on again. What do I do now??