Multi-DB

Urgent - please help

I have another thread that I started and I hate to start another, but I know how the support works - if I update it it will show that it's been replied to and I won't get a response.

I'm having problems with Multi-DB, which I was trying to troubleshoot myself and now it's gotten worse. I noticed something I overlooked in the db-config.php file, two mistakes I made in the global db settings. I fixed these and re-ran the move-blogs.php script. Now my whole site is inaccessible. Going to a site shows:
Warning: mysql_set_charset() expects parameter 2 to be resource, boolean given in /home/myusername/public_html/wp-includes/wp-db.php on line 554

Warning: Cannot modify header information - headers already sent by (output started at /home/myusername/public_html/wp-includes/wp-db.php:554) in /home/myusername/public_html/wp-includes/functions.php on line 2540
Error establishing a database connection

Trying to get to the wp-admin area, I get the following error:

Warning: mysql_set_charset() expects parameter 2 to be resource, boolean given in /home/myusername/public_html/wp-includes/wp-db.php on line 554
One or more database tables are unavailable. The database may need to be repaired.

Please help!