Satnav screen failure

[DaveyTed]

Hi All,
Re: 2021 hybrid Ultimate.
I purchased the car about six months ago and the satnav screen now fails to light up sometimes when starting the car. It will work normally on restart after a few hours.
It's been back to the dealer but nothing shows up on a diagnostic check. I have shown the service department a video of the fault I took on my phone. I've also parked and locked the car and the screen has come back on after initially shutting down.
Any suggestions?
TIA