Thanks for the advice. I followed KITPROG2_User_Guide instructions:
1: Snaped off Kitprog on-board Programmer / Debugger was pluged direct without cable to USB port
2: Power LED2 is on, Status LED3 in on for 0.1 s then off
3: Entry for this LED state in KITPROG2_User_Guide Table 8-1 Meaning of KitProg2 LED Indications is:
USB enumeration is unsuccessful.
KitProg2 is in low power
4: There is no change in listed devices in device manager window, when KitProg printed circuit board is disconnected and reconnected to USB port. In all probability USB enumeration is unsuccessful.
5: I followed steps in KITPROG2 UG 4.1 Enter or Exit the Mass Storage Programmer Mode
Step a) Press and release the mode switch (SW2) on the kit after the Amber Status LED has turned off. -> OK it happens!
Step b) in description: The KitProg2 re-enumerates as the Mass Storage Programmer/CMSIS-DAP programmer if the
previous configuration is KitProg2 Programmer and Debugger. -> This happens not. There isn't any change or new entry in device manager window.
Test: Using another exemplar of Snaped off Kitprog on-board Programmer / Debugger all steps worked like described in KITProg User Guide.
Summary: By holding switch SW3 pressed for some seconds state of LED3 can be changed from LED3=off to LED3=breathing
at a rate of 1Hz and reverse. But never to the state LED3=on and always without any new entry in device manager window.
Looks like a fried Kitprog...
I' ll take a new KitProg ..