What would happen if I backed up the NAND of my friend's wii, and then installed it into my wii?
I'm just curious.
If you have the keys file for your Wii it may work. The other scenario is it will say something like nand is for another Wii and won't let you restore his to yours. I would not recommend that you restore another Wii to yours you may inheret any problems that he has and is unaware of them.