This is the most tragic scenario. You tried a risky mod, the Wii now shows a black screen or an error message, and you have no personal NAND backup.
This article explores what Wii NAND backup files are, why you might need to download them, how to create your own, and the risks involved. What is a Wii NAND Backup File?
A is an exact digital clone (a .bin file) of this internal memory. Think of it as a total system restore point. If software modification goes wrong, flashing a clean NAND backup returns your console to the exact state it was in when the backup was created. Why You Cannot Just Download a Wii NAND Backup Online