I updated the MySQL ispconfig user password by connecting to mysql and running the sql to change the password.
mysql -u root mysql
mysql> update sys_user set passwort = md5('isptest') WHERE username = 'ispconfig';
Then I typed the same password into an MD5 generator http://www.iwebtool.com/md5
I pasted that MD5 password into my config.inc.php file.
$conf['db_password'] = 'PASTEDMD5PASSWORD';
I can now login to ispconfig.
Thank you for your help.