What is the VCSA version?
If it is VCSA 6.x, can you check if the services are started or kindly check the certificates if they are expired?
BTW -> vmware-sso is only 5.1 vcsa service
service-control --status --all shows the service status in 6.x
If VCSA 5.x -> try to access https://VCenterFQDN:7444/lookupservice/sdk -> on the browser and check the certificates are active or expired.
If expired, you need to use this KB VMware Knowledge Base
Thanks,
MS