This is just a sanity check, but I just cloned my brother’s hard drive using dd if=/dev/sda of=/SOMEWHERE/DISK.iso (with batch size and status=progress), but the last time I did this, the OS wouldn’t boot.
I’m trying it again (obviously with the sister command dd if=DISK.iso of=/dev/sdb). Does this result in a bootable internal HDD? (These drives are on 2 seperate systems, hence the .ISO intermediate step).
This is technically for a Windows system, but I did the cloning using a manjaro live USB