Squid Blackout

Hello, sometimes (it happened 3 times) my Squid suddenly turns lights and displays off for seconds, then continue to work but with all buttons and pads lights off... to put it back in normal conditions I have to turn off, remove power supply cable then connect again and turn it on.

if I just try to turn off and on again, it works but still with no lights except global, tap, play and rec buttons, if I remember well.

thank you