After changing domain, Wordpress does not connect to database, user does, before the change, WP was working

Jobs
4

Thank you for your time in answering @calport and @Gomez_Adams

  1. In wp-config.php I commented the line:
    /** define(‘DOMAIN_CURRENT_SITE’, ‘newdomain.com’); **/
    And when ran …://newdomain.com/index.php it sent me to the old domain with the corresponding error not finding it.
    We can’t connect to the server at olddomain.com

  2. I created a new DB user and new random generated password, via Edit Databases in the Virtualmin account, while doing this I ran again: …://newdomain.com/index.php and got this obvious error, because I had not changed yet the user in wp-config.php

Warning: mysqli_real_connect(): (HY000/1045): Access denied for user ‘originaluser’@‘localhost’ (using password: YES) in /home/account/public_html/wp-includes/wp-db.php on line 1653

Access denied for user 'originaluser'@'localhost' (using password: YES)

Error establishing a database connection

This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server at localhost. This could mean your host’s database server is down.

  • Are you sure you have the correct username and password?
  • Are you sure you have typed the correct hostname?
  • Are you sure the database server is running?

If you’re unsure what these terms mean you should probably contact your host. If you still need help you can always visit the WordPress Support Forums.

  1. I changed the user and password for the new one created and I got, the same original one line error, with no more details:
    # Error establishing a database connection

I do not know what else to do, the problem is that this is was working before the change of domain name on the Virtualmin account.
Any more ideas are welcomed, thanks in advance.