After issuing hostname SSL, you can bring CyberPanel back online (in case it goes down) with systemctl restart lscpd
However, if you can’t boot your VPS, you need to contact your provider. yum update might have broken some things for you, but you need to contact your provider.
I can boot the server to a rescue OS linux OS (it’s a dedicated server with OVH). How can I get to issue the command “systemctl restart lscpd” ? OVH, the hosting provider, don’t offer much support apart from hardware problems.