I do not know if I did understand instructions for downgrade fully but this is how I did it. Please tell me if it right...
I downgraded my wii with
IOS51 Update Removal and Patch Fix
I used wad manager v 1.3
I run first ios16-64-v257.wad then
cios fix.wad then
ios36-64-v1042.wad
My wii...