Failed to create/backup SQL SSB certificate - on restore to new server

Hi, I have just built a new server W2019, SQL 2017cu31 and all the other pre-reqs and ran a full restore using a full backup. It all goes well until the end where it says

INFO: SQL Connection succeeded. Connection: SMS ACCESS, Type: Secure Configuration Manager Setup 10/12/2023 20:50:07 2364 (0x093C)

Create_BackupSQLCert : SQL server failed to backup cert. Configuration Manager Setup 10/12/2023 20:50:19 2364 (0x093C)

CSiteControlSetup::SetupCertificateForSSB : Failed to create/backup SQL SSB certificate. Configuration Manager Setup 10/12/2023 20:50:19 2364 (0x093C)

ERROR: Failed to set up SQL Server certificate for service broker on "ISVSCCM.fqdn" . Configuration Manager Setup 10/12/2023 20:50:19 2364 (0x093C)

ERROR: Failed to initialize the site control data. Configuration Manager Setup 10/12/2023 20:50:19 2364 (0x093C)

INFO: SQL Connection succeeded. Connection: SMS ACCESS, Type: Secure Configuration Manager Setup 10/12/2023 20:50:19 2364 (0x093C)

In the pre-requisite checks- it failed on S__QL Server service running account__- so i created a domain user account to run it, and it continued.

I did find this-https://adamcook.io/p/configmgr-database-move-failed-to-create/backup-sql-ssb-certificate/

but i have no idea what to do now. (We use bitlocker mgmt in confimgr if that is relevant (but didnt create a specific cert for this))- can i do something to fix this? and/or will i have to run the restore again?

Please can someone help- the site has been down for almost a week due to a failed IPU. I thought the full restore onto a new server, but no idea what to do now.

Thanks