Hi marianoT,
Please check if PTA1 and PTA2 are connect. These two pins are the default UART pads used by the Kinetis ROM Bootloader.

Press PTA4(NMI_b) pin before power on, then click the Connect button on KinetisFlashTool.

I don't have mkl17z32vlh4 by my side, so I tested it on the FRDM-KL27Z development board.
1. Press SW1
2. Plug the USB cable to J13

Best Regards,
Robin
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