SCOM 2016 installation fails due to login failed error

During SCOM 2016 install the DB installation fails - When I look in the install log it says the login failed, but it’s got sysadmin?

Keep in mind that during DB creation the user requires privileges to create the files on the location where the data and log files are made during installation.
So you’ll need local administrative permissions on the SQL box as well.

Take a look at this post by Stefan Roth:

If you haven’t already then it’s worth following along with Kevin Holman’s guide. Are you all 2016 i.e. SQL 2016, Windows 2016?

What does the SQL log say? Can you get some extra info regarding the login failed?

It’s not something unrelated to permissions, such as firewall blocking between management servers and DB server?

I found this in the setup log:

Error: :Exception running sql string [NOT DEFINED]: Threw Exception.Type: System.Data.SqlClient.SqlException, Exception Error Code: 0x80131904, Exception.Message: Cannot open database “OperationsManager” requested by the login. The login failed.
Login failed for user ‘Domain\User’.

SQL logs just echo this…