Misc CFW and NNID transfer troubleshooting

[C18266]

Recently, I helped a friend or mine to have his console with CFW using the DSi exploit with my actual console which has already games . Using this, my NNID transferred to the other console and after that I restored the previous NAND on my console. Soon after I noticed that my friend and I were using the same NNID. I heard about that you have to wait a week to transfer back the NNID to my system.

I don't know if that means that he's going to lose his save data and mine too. What can I do? I'd really don't want lose any data on my console. Hope you guys can help me.

 

[ChaosWeeb]

Well if he completed the CFW, tell him to make a nand backup and backup his SD Card data. Then transfer over then after, when his system memory is formatted, tell him to put files on SD Card from sd backup then tell him to restore Nand backup, then follow
Removing an NNID without formatting your device from the Troubleshooting section of 3ds.guide to remove your NNID from his system. And profit! You have your NNID back and its not on your friends anymore