turn the switch on. Mine did this once and i switched the switch around and it came to. Also make sure you have all updates installed (firmware, latest castle link etc...)
I think you need to update to the newest version of the Castle Link v3.051. The newest version of the firmware is still 3.17. If you are using v3.051 try uninstalling and reinstalling. I had this problem when I first got my MMM but
I can't remember what the cause was exactly. I think it was because I was using v3.04.