1) I have an Ubuntu system which I cloned to an external disk using dd
dd if=/dev/sde of=/dev/sdf bs=4096 conv=notrunc,noerror
2) I then changed the uuid of the external disk (/dev/sdf) to a new UUID
tune2fs /dev/sdf -U numbergeneratedbyuuidgen
3) I then rebooted the whole system. The external USB disk was mounted to mount point /media/numbergeneratedbyuuidgen
4) I edited the /media/numbergeneratedbyuuidgen/boot/grub/grub.cfg I changed all the mentions of the old UUID to numbergeneratedbyuuidgen
5) I edited /media/numbergeneratedbyuuidgen/etc/fstab Here I also changed all mentions of the original UUID to numbergeneratedbyuuidgen
Now when I reboot. I ask the machine BIOS to boot from USB disk . But nothing happens.
My questions are: What do I have to do to get grub on the cloned drive to kick in. Is there a step I am missing and can I execute that step booted into my parent install , i.e without a livecd.
There are closely related questions on askubuntu but the most relevant one suggests to use clonezilla and the other one remastersys. I feel I am one step away from getting grub setup right on the cloned drive to have it boot from the parent bios and dont want to resort to either solution.