You're absolutely right.
Manual said reset button should be pressed twice within 5 seconds to rollback to factory reset, i did it so many times, nothing happend.
I just upgraded my JVC "KD-X330BTS" unit firmware from ver.0106 to ver.0123, the process completed and the unit rebooted successfully.
Unfortunately, after that Bluetooth feature didn't work, either in "source" button or by "settings", all the time keep giving me "PLEASE WAIT" then "H/W ERROR"...