Had to do something similar
Made a Proper copy of it and a brick blocker version.
This is for a PAL 3.0E firmware wii
i put the brick blocker version (You know the one with the update removed)
Got a black screen so swore at teh wii ;-)
Booted up the backup untouched let it do a update for about 15% pulled the main out the back rebooted the wii.
Then loaded up the brick blocker version and it worked fine.
Dont even get that double channels problem