hello zjfsharp,
here’s one way you may have a try,
first, generate the eks_sigheader.img.encrypt with your own keys by l4t_sign_image.sh.
check the partition label, $ ls -al /dev/disk/by-partlabel of your target.
for example, eks -> ../../mmcblk0p12
after that,
please copy the binary by scp to your target, using the dd commands to update eks partition.
i.e. $ sudo dd if=eks_sigheader.img.encrypt of=/dev/mmcblk0p12
perform a warm-reboot to have the update takes effect,
thanks