well... sd card thing is just nintendo's bait to fish all the noobs.
when 4.0 with sd was first released, i told you that after a month, there will be so many people who updated to 4.0 mindlessly and cry on this board.
i guess i was exactly right.
That doesn't work if you updated through Nintendo, as the signing bug will have been fixed on all IOS versions. Anyway, if the signing bug still worked, you could just use the Homebrew Channel installer ISO to install it to your Wii console.
um i updated to 4.0 thru WANNIKOS 4.0 updater.... and I can downgrade anytime I want so Im not crying. People have ALWAYS been warned NEVER to update thru Nintendo ever since the Wii homebrew scene emerged. Anyways, i read some where that if u run CIOSCORP and put System-MenU 289 NTSC.WAD in the folder it will downgrade u to 3.2U from 4.0... if it bricks, then I dont accept any responsibility. but someone on here successfully downgraded that way.
Umm.... am I mistaken in thinking that my Wii is on SM4.0? (I haven't turned it on for a while so I can't remember) I seem to remember upgrading to SM4.0 using Waninkoko's update tool... I may be mistaken... all this coding is making my memory go fuzzy
EDIT: Sorry, this took a long time to post, and after it finished I noticed a new post (which is above mine right now), so it pretty much answers my doubt, lol.