Cuav X7 pro doesn't connect to Mission Planner via USB

connecting an USB cable to the FC starts the green LED blinking for a few seconds, after that the LED is permanently on . Unfourtunately when I try to get a connection to MP on my PC the following message appears:

Does anybody had a similar problem ? Is there a possibility to reset the device ( factory reset ) ?
The " BOOT " switch on the Alu-Body didn’t help…

Kind Regards