rear tv screens not working

I bought a l322 vogue yesterday and took the children for a drive the vehicle has rear dvd screens in the head rest that don’t seem to turn on which is bugging the children any ideas on how they switch on or a fix..I have checked all fuses all ok they just don’t seem to be getting power

Many thanks

If you just bought it, take it back for them to show you how to turn them on, or for them to fix it!