How to restore user mapping for windows account after database restore

I have restored a database to a development server from our outside contractor.  I need to relink the user mapping of devdomain\devservice to the login of the same name in database ProductContentDB.


I have executed ALTER USER [devdomain\devservice] with login = [devdomain\devservice] in ProductContentDB, but the User Mapping under the login in the security are still shows the mapping to be missing.  There is also a downarrow over the login when I look at the login in the database security.

I would appreciate your insight on how you usually restore user mapping