Out of the blue today, my MC6 Pro just started going into this endless loop of restarting. It first started happening while I was trying to program an Expression Message.
Powering off then on doesn’t fix the issue. Removing all connections doesn’t resolve it. Have also tried changing power sources.
I realised safe mode does not stop the expression presets from being sent. Can you try loading the firmware below and then booting it in safe mode again and see if you can get it to load?
You can also enter the global config menu (Hold down D while booting up), then navigate to “Enter Global Config” and then set the Omniports to something else like MIDI OUT, and then see if that helps.