Bootloader upload via st-link/v2 problems

I want to load the px4fmuv2_bl.bin and the px4IO_bl.bin with ST-Link/v2 via JTAG and then connect the px4
with the bootloaders installed via usb to missinplaner and download the firmware.

I managed to download the Bootloaders to the FMU:s. I can see the FMU-leds blinking rapidly in amber so it means that the bootloaders are in place and active.
But when I connect the px4-board to the computer the computer doen,t recognize the hardware.
I have the px4 drivers installed and working (tested with another px4) but I am still getting a “error code 43” on the usb.

What am I doing wrong?

Thanks in advance!

This was a faulty hardware problem.
Two new boards in a row