I recently had a problem logging into System Platform. I could not connect to the CDOM via the web, nor SSH into DOM0. Fortunately, there is a way to reboot the S8300D from the gateway itself. Log into the gateway as root, then type “configure” to get to the config menu. Then simply type “reset mm v1”, which will reboot the media module in slot V1. Confirm, and the card will reboot. From my understanding, it will cleanly shut down each VM and reboot.
As always, it will take just long enough for you to panic, plus 45 seconds or so.