Help!

[Shonumi]

You need to be more specific. What exactly have you done so far (name the NAND tools you've used) and what is the exact error you keep running into?

After that, have you followed this guide step-by-step?

https://wiki.dolphin-emu.org/index.php?title=NAND_Usage_Guide#Dumping_NAND_with_BootMii