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You still can't downgrade, install a cIOS lower than r12 or install cioscorp
Found this on gbatemp, some people are having success with it so it is worth trying
It uses wiigators cboot2 to run a special wad manager that in turn you can use to install the LU64/65 fix.
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1: Copy contents of 'SD Card 1' to SD card.
2: Put card in Wii and go to Data Management > channels > SD Card, then you will get a message saying "Load boot.elf? Select 'Yes'.
3: Install Bootmii v2 as an IOS.
4: Install the Homebrew Channel
5: Remove SD card and save the Bootmii installation to your PC.
6: Delete Bootmii installation off of your SD card and copy contents of 'SD Card 2' to your card.
7: Now put card back in, restart your wii ,start HBC, press home then run Bootmii.
8: The screen will be black for 10 seconds then Wad manager will run.
9: Select
uninstall first then install IOS16.wad and do the same for LU64.wad.
10: Go to HB channel and run cIOS38_rev13b-Installer.
11: Done, now you can install a backup loader or usb loader.
guide orig posted by flavors, i just made it a bit (lot) more user friendly
If you want Preloader on your LU64 then have a look
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