Thanks for the responses guys,
I have console access to all controllers using OpenGear's IMX4216 for console access.
Issue was, for the past couple weeks we've been dealing with the bug just fixed in yesterdays 6.3.0.2 release... we were rebooting a production m3 controller almost once a day. But when they locked up - they were inaccessible via ssh/ http/ or console. So none of that would have helped. Couldn't kill power to chassis because the other controller was handling the failed over AP's. Soooo SOL until I show up and pulled the card out.
Thanks again though, especially clever use of the raspberry pi!