Hi!
The “blue rectangle” contacts are all you need. You should use the guide described as SWD:
-
Once you solder the cables to the mentioned contact pads, you need to connect them to debug
adapter’s respective inputs (as described in the docs or on its case).
You can find more on the hobbyist pages, e.g.: -
Then using OpenOCD or STM’s official tool you can flash the new firmware (however all user data will be removed with that operation).
Example soldering for SWD operations (development hardware; “red rectangle”):
Connected:
PS You can probably avoid on-device soldering with the Nitrokey Pro hardware you have, when using the DFU approach (it requires making custom adapter to serial communication though) :