2020 defender HD5 rear diff won’t disengage

[Jbousman88]

New purchase on 2020 defender.  Dealer has been little help.  4wd fuse was popped.  Replaced and have that working.  Rear diff will not unlock.  Dealer can look at unit next Tuesday but I wanted to know if anyone knows how to fix or what relay this may be.  Any input would be helpful.