Skoda radio navigation problem

Hopefully this is a simple fix but it's not in the manual. The background is we have a factory fitted radio/satnav unit it's double din LCD but not touch screen, buttons down either side two knobs one either side. Think it's blaupunkt but not sure. It's a Skoda octavia 2.0 fsi VRS mkii 2006. The problem is the unit doesn't turn on when you turn on the engine you can start the unit normally and turn it off with the knob but it used to come on automatically with the ignition. One of the kids has probably been messing with the controls and disabled it so if anyone knows how to get it to come on automatically agin then that would be great.