Was performing some checks on an environment and decided to check to see what SCOM was reporting. Open SCOM Console. Running SCOM 2012 R2 on Windows Server 2008 R2.
Couldn’t Connect. No descriptive error.
Opened Event Viewer, expanded Applications and Services Logs and click Operations Manager.

Found the following error that advised that I had exceeded the evaluation period.

To resolve, you need to licence SCOM with a valid licence.
Opened Operations Manager Shell on the Management Server and run the following script:

Set-SCOMLicence –ProductID 'ProductKey'