500 Internal Server Error... one multi-db (out of 23) subdomain not available...

Good morning,

would be great if you could advice on how to solve the following issue:

Link last checked: 09/02/2015
HTTP code: 500
Response time: 0.510 seconds
Final URL: http://superintendence.bestofthebestonly.com/
Redirect count: 0
Instance count: 1

This link has failed 4 times.
This link has been broken for 2 days.

Log: === HTTP code : 500 ===
HTTP/1.1 500 Internal Server Error
Date: Mon, 09 Feb 2015 13:17:09 GMT
Server: Apache
Vary: Accept-Encoding
Content-Length: 0
Connection: close
Content-Type: text/html

Background: Two days ago installed redirect plugin but with wrong settings I locked me self out even as super admin. Though I deinstalled plugin which solved the problem for in total MainDomain plus 22 subdomains BUT only on one, as shown above the redirect (to a white page... also no access to subdomain at all) still occurs.

Please let me know if you need server access to go into the issue. Will forward needed credentials immediately.

Thank you in advance.
Looking forward hearing from you soon.
Prinz