Reading at your thread, its seems we have the same issue
Did the solution sugested by DaneLLL worked out for you?
Hi,
If you have your self-built kernel, please do apt-mark hold the packages:
nvidia-l4t-display-kernel nvidia-l4t-kernel nvidia-l4t-kernel-dtbs nvidia-l4t-kernel-headers nvidia-l4t-kernel-oot-headers nvidia-l4t-kernel-oot-modules
So the the kernel is not overwritten to default kernel. Updating other packages should be fine.