This is a long story to explain. I had a old post on jetson nano forum which explained a little.
Basically, you could only use the commands with initrd flash command to flash your jetson orin nano/nx. It is same command you are using in the beginning.
Could you flash your “xavier nx” with flash.sh first, boot it up and see if you see the xavier nx device in your lsusb command on host PC? If you can see it, please ping it using the usb interface IP.