I am not using the FRDM-MCXW71 board, but a homemade board with a brand new MCU.
After entering ISP mode and using the command, the obtained serial port properties are the same, but uploading the firmware is unsuccessful. It might be an issue with the SB file.

May I ask if there is a pre-burned file on the development board? Or how to create a Custom SB file?
where can the required certBlock certificate and signer Image files be found, and could you provide detailed methods or files?
Operate according to the information provided:
- Open a workspace for with the custom keys that were provisioned to the deviceKW45xx/K32W1xx/MCXW71xx/KW47xx/MCXW72xx

- Copy NBU firmware into workspace as source_images\nbu_firmware.xip
Change the file name to nbu_firmware。
3. In the menu bar, select Tools > SB Editor
4. Fill the Properties tab or import a setting from the SB file created on the Build tab

Where can the nbu_firmware.xip and certBlock files be obtained? To implement wireless communication functions such as Bluetooth and ZigBee.