Before you upgraded, your user name was Admin? And the password worked.
Why do you think after the upgrade, your user name is now DBA? Was it changed in the console after the upgrade?
Are you using Active Directory synchronization?
If you used the resetpass.bat, have you tried admin/admin?
You can try running a repair on the server, it will once again ask you to input an admin password.
Last thing to check, it is possible that your CAPS lock was on when you entered your password. Try turning on CAPS lock and entering your password.
The only other thing I can think of, that sometimes makes the system unhappy, is when certain special characters are used and it cannot interpret them for longin.