SQL Server Service Account login or password is not valid error
The issue isn't with the account you are attempting to use, but your account. If you look in the setup log file, which is created during the installation of the SQL Server application, you will see the details of the issue, with technical jargon that will indicate the issue is probably a permission issue with your account having permission to perform a check on the service account credentials:

Slp: Sco: Attempting to check if container ‘WinNT://DOMAIN’ of user account exists
Slp: UserSecurity.ValidateCredentials — Exception caught and ignored, exception is Access is denied.
Slp: UserSecurity.ValidateCredentials — user validation failed


Rebooting usually fixes this issue, as does changing the service account value after installation is complete. A minor issue that sometimes appears.