Thanks guys. I got it.
"localhost' was capitalized for whatever effed up reason after the downtime under /inc/config.php like so:
$config['database']['hostname'] = 'Localhost';
In case anyone else runs into this problem.
I've used altartbu with no problems until now. The user name wasn't...
This is the second time it's happened when the host goes down. Another x10 site I'm affiliated with went down as well, but the 1045 didn't start there.
This happened once before out of the blue. I went to the myBB forums and found a solution but it isn't the PW this time. Have added the username 'admin' using the link provided, and the error keeps occurring.