The Data Access service is unable to connect to the Operations Manager database. When the Data Access service is not running, users will not be able to use the Operations Console, Web Console, or Command Shell. Any connectors to 3rd party management systems will not work as well.
Check the database server on which the Operations Manager database is installed to make sure its online and the Operations Manager database is online.
Make sure the database server is reachable from the server where the Data Access service is installed.
Make sure the SQL server accepts remote connections using SQL Server Configuration Manager.
Make sure the account used by the Data Access service has sufficient privileges to access the Operations Manager database.