Backup and format the sd-card. Then extract CB2_BB2_Dop-Ios_Mod-v11.5.zip to the sd-card. Click the sd icon and load the boot.dol/elf.
Use ios249 or install ios36 with fakesign and use ios36 if you don't have ios249.
Install ios60 with patches, then install system menu 4.1 for your region.
If your wii is offline, use CB2_BB_Wad-Manager-1.4.zip with ios249, extract to sd:\
Extract IOS60-patched.zip to sd:\wad
and your system menu wad to sd:\wad
If you still have trouble with your sd-card, try to format with this tool.
Install system menu 4.1