Screen Sharing frozen - Can't SSH into Xserve

Long story short: I was trying to backup one of the partitions from our University's Xserve (yes, we still have those) using Carbon Copy Cloner, and it was running way too slow. I configured it to create a sparseimage of the partition and send it straight to a remote AFP share which is actually an external harddrive connected to my office iMac, but it was only averaging 24KB/s across our gigabit network. I was able to stop the cloning process but couldnt quit the application (keep in mind I'm doing all this via Apple Remote Desktop). So, I opened Terminal and ran "killall", but nothing happened. Then I tried to logout...nothing. Then I tried to restart...nothing. I decided to SSH into the Xserve and ran the "reboot" command. Nothing. Then I ran the "shutdown -r now" command and got this message after every attempt to SSH into it again:

NO LOGINS: System going down at 17:04

Permission denied (publickey,gssapi-keyex,gssapi-with-mic,keyboard-interactive).

So...now I cant SSH nor remotely control the server. Great! ARD says that screensharing is available, I can view the frozen screen which only shows the dock. However I cant do anything else because "Client software not active". Now I'm panicking. I dont have physical access to the Xserve because its located in the Data Center. And I cant get the guy who works in there to manually reboot it for me because other departments are using the server as well. How can I regain access to my server via SSH or ARD? Please help!