1. Ensure the certificate is installed in the computer store of all the AD FS servers in the farm
2. Grant permissions to the digital certificate to the ADFS Service account. Do this by right-clicking the new digital certificate in the MMC snap-in for certificates and choosing All Tasks > Manage Private Keys. Grant read permission to the service account that ADFS is using (you need to click Object Types and select Service Accounts to be able to select this user). Repeat for each server in the farm.
3. In the AD FS management console expand service > certificates and ensure that the service communications certificate is correct and that the date is valid.
4. Open this certificate by double-clicking it and on the Details tab, check the value for the Thumbprint.
5. Start PowerShell on the AD FS Server and run Get-AdfsSslCertificate (not Get-AdfsCertificate). You should get back a few rows of data listing localhost and your federation service name along with a PortNumber and CertificateHash. Make sure the CertificateHash matches the Thumbprint for the service communications certificate.
6. If they do not, then run Set-AdfsSslCertificate -Thumbprint XXXXXX (where XXXXX is the thumbprint value without spaces).
7. Then you need to restart the ADFS Server.
8. Repeat for each member of the farm, taking them out and in from any load balancer configuration you have. Ensure any SSL certs on the load balancer are updated as well.