Sorry for the 'lack' of detail, and no i have not spoken to Microsoft support, (didnt even know i could ?) Using Monitoring > site status> i can see that State Migration Point and Management Point both show critical errors and they're the same ID's for both roles, Not sure if this may shed a little light on things or Jog a memory ?
1016 - not much help
"Site Component Manager failed to install this component on this site system. Solution: Review the previous status messages to determine the exact reason for the failure. Site Component Manager will automatically retry the installation in 60 minutes. To force Site Component Manager to immediately retry the installation, stop and restart Site Component Manager using the Configuration Manager Service Manager."
4960 - most helpful error message but World Wide Publishing service is started on the server in IIS.
"Site Component Manager failed to install this component, because the designated Web Site of Internet Information Services is not running or started. Possible cause: The designated Web Site is in the Stopped or Paused state. Solution: Start the designated Web Site using the Internet Services Manager. Possible cause: The World Wide Publishing Service is in the Stopped or Paused or Disabled state. Solution: Start the World Wide Publishing Service on the machine. Site Component Manager cannot install component SMS_STATE_MIGRATION_POINT until the designated Web Site is started. Refer to your ConfigMgr Documentation or the Microsoft Knowledge Base for further information."
4951
Site Component Manager failed to install this component, because the Microsoft Installer File for this component (bgbisapi.msi) could not install. Refer to the BgbSetup.log, the bgbisapimsi.log, as well as the ConfigMgr Documentation and the Microsoft Knowledge Base for further information.
4951 is mentioned in one of your posts:
https://www.prajwaldesai.com/fatal-msi-error-bgbisapi-msi-could-not-be-installed/ but we are installing on C:\ not in an alternate location although i tried the file amendment out of pure frustration !
BgbSetup.log:
<02/05/21 09:32:09> ~RoleSetup().
<02/05/21 10:07:08> ====================================================================
<02/05/21 10:07:08> SMSBGB Setup Started....
<02/05/21 10:07:08> Parameters: C:\Program Files\Microsoft Configuration Manager\bin\x64\rolesetup.exe /install /siteserver:SCCMWSUS SMSBGB 0
<02/05/21 10:07:08> Installing Pre Reqs for SMSBGB
<02/05/21 10:07:08> ======== Installing Pre Reqs for Role SMSBGB ========
<02/05/21 10:07:08> Found 1 Pre Reqs for Role SMSBGB
<02/05/21 10:07:08> Pre Req SqlNativeClient found.
<02/05/21 10:07:08> SqlNativeClient already installed (Product Code: {B9274744-8BAE-4874-8E59-2610919CD419}). Would not install again.
<02/05/21 10:07:08> Pre Req SqlNativeClient is already installed. Skipping it.
<02/05/21 10:07:08> ======== Completed Installation of Pre Reqs for Role SMSBGB ========
<02/05/21 10:07:08> Installing the SMSBGB
<02/05/21 10:07:08> Passed OS version check.
<02/05/21 10:07:08> IIS Service is installed.
<02/05/21 10:07:08> No versions of SMSBGB are installed. Installing new SMSBGB.
<02/05/21 10:07:08> Enabling MSI logging. bgbisapi.msi will log to C:\Program Files\Microsoft Configuration Manager\logs\bgbisapiMSI.log
<02/05/21 10:07:08> Installing C:\Program Files\Microsoft Configuration Manager\bin\x64\bgbisapi.msi CCMINSTALLDIR="C:\Program Files\SMS_CCM" CCMSERVERDATAROOT="C:\Program Files\Microsoft Configuration Manager" USESMSPORTS=TRUE SMSPORTS=80 USESMSSSLPORTS=TRUE SMSSSLPORTS=443 USESMSSSL=TRUE SMSSSLSTATE=0 CCMENABLELOGGING=TRUE CCMLOGLEVEL=1 CCMLOGMAXSIZE=1000000 CCMLOGMAXHISTORY=1
<02/05/21 10:07:10> bgbisapi.msi exited with return code: 1603
<02/05/21 10:07:10> Backing up C:\Program Files\Microsoft Configuration Manager\logs\bgbisapiMSI.log to C:\Program Files\Microsoft Configuration Manager\logs\bgbisapiMSI.log.LastError
<02/05/21 10:07:10> Fatal MSI Error - bgbisapi.msi could not be installed.
bgbisapiMSI.log:
Property(S): Date = 05/02/2021
Property(S): MsiNetAssemblySupport = 4.7.3190.0
Property(S): MsiWin32AssemblySupport = 6.3.17763.1
Property(S): RedirectedDllSupport = 2
Property(S): MsiRunningElevated = 1
Property(S): Privileged = 1
Property(S): DATABASE = C:\WINDOWS\Installer\4bb27d9.msi
Property(S): OriginalDatabase = C:\Program Files\Microsoft Configuration Manager\bin\x64\bgbisapi.msi
Property(S): UILevel = 2
Property(S): ACTION = INSTALL
Property(S): ROOTDRIVE = E:\
Property(S): CostingComplete = 1
Property(S): OutOfDiskSpace = 0
Property(S): OutOfNoRbDiskSpace = 0
Property(S): PrimaryVolumeSpaceAvailable = 752630056
Property(S): PrimaryVolumeSpaceRequired = 15124
Property(S): PrimaryVolumeSpaceRemaining = 752614932
Property(S): INSTALLLEVEL = 1
Property(S): PrimaryVolumePath = C:
Property(S): SMSCWSID = 1
Property(S): SOURCEDIR = C:\Program Files\Microsoft Configuration Manager\bin\x64\
Property(S): SourcedirProduct = {66FC5429-0E98-4CD0-B113-F8D788EDF6D6}
Property(S): ProductToBeRegistered = 1
MSI (s) (F8:2C) [10:07:10:397]: Note: 1: 1708
MSI (s) (F8:2C) [10:07:10:397]: Product: BGB http proxy -- Installation operation failed.
MSI (s) (F8:2C) [10:07:10:397]: Windows Installer installed the product. Product Name: BGB http proxy. Product Version: 5.00.9040.1000. Product Language: 1033. Manufacturer: Microsoft Corporation. Installation success or error status: 1603.
MSI (s) (F8:2C) [10:07:10:400]: Deferring clean up of packages/files, if any exist
MSI (s) (F8:2C) [10:07:10:401]: MainEngineThread is returning 1603
MSI (s) (F8:9C) [10:07:10:402]: RESTART MANAGER: Session closed.
MSI (s) (F8:9C) [10:07:10:402]: No System Restore sequence number for this installation.
=== Logging stopped: 05/02/2021 10:07:10 ===
MSI (s) (F8:9C) [10:07:10:405]: User policy value 'DisableRollback' is 0
MSI (s) (F8:9C) [10:07:10:405]: Machine policy value 'DisableRollback' is 0
MSI (s) (F8:9C) [10:07:10:405]: Incrementing counter to disable shutdown. Counter after increment: 0
MSI (s) (F8:9C) [10:07:10:405]: Note: 1: 1402 2: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Installer\Rollback\Scripts 3: 2
MSI (s) (F8:9C) [10:07:10:405]: Note: 1: 1402 2: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Installer\Rollback\Scripts 3: 2
MSI (s) (F8:9C) [10:07:10:405]: Decrementing counter to disable shutdown. If counter >= 0, shutdown will be denied. Counter after decrement: -1
MSI (s) (F8:9C) [10:07:10:406]: Destroying RemoteAPI object.
MSI (s) (F8:58) [10:07:10:406]: Custom Action Manager thread ending.
MSI (c) (DC:78) [10:07:10:407]: Decrementing counter to disable shutdown. If counter >= 0, shutdown will be denied. Counter after decrement: -1
MSI (c) (DC:78) [10:07:10:407]: MainEngineThread is returning 1603
=== Verbose logging stopped: 05/02/2021 10:07:10 ===