To start with, is this partition an actual partition, or is it a file? If a partition, what designation, such as “/dev/mmcblk0p32”? Assuming it is “/dev/mmcblk0p32” (adjust for your actual case), what do you see from:
lsblk -f /dev/mmcblk0p32
If this is a file, then let me know for different instructions.
Note that you wouldn’t use dd to copy filesystem.img to that partition unless the two were exact matches in size. If that partition is not mounted anywhere, then are you able to mount and umount the partition? Does this work:
sudo mount /dev/mmcblk0p32 /mnt
sudo umount /dev/mmcblk0p32
Also, your dd must specify both a source and a destination. The source (input file) is the “if=” option, the destination is the “of=” option. If you are using a file and not a partition, then the file must also be writable permission for whoever it is being mounted as…there are options for this setup. I have not looked at the options to know who this file shows up for, but while testing, if and only if we are using the original “filesystem.img”, then this might be a valid temporary step for configuration of one part of the permissions:
sudo chmod ugo+rw /opt/nvidia/l4t-usb-device-mode/filesystem.img