Garmin Express crashed it?
I know it should be ok but just to be sure, look at garmin device.xml in Garmin folder in your backup and look at these lines at the beginning:

Code:
Please Login or Register to see the links
Where 0xxx is your firmware HWID.
zumo660_GCDFile__510.gcd is 924

If cure+formatting by RMPrepUSB+flashing original fw, doesn't work sorry I'm afraid you need kunix here