Hi,
All you can do in this scenario, turn it off, back on, and again try the console connection(using straight-thru cable), you should be able to break into the box to load the last saved CONFIG, or just rename the CONFIG.BAK to CONFIG, and reboot the box again.
If that doesn't help, try using the web interface, by connecting the PC to the inside network, and see if u can ping, then try http from there.
If nothing works, it would be better to open up a TAC case to get helped if possible.
Thanks
Afaq