jesta
Moderator
"Maintenance Mode; What does it do? Well, it switches off your Wii Message Board (don’t worry, next time you turn on your Wii, it will be fine). But, others that have tried it have gotten their Systems Settings disabled (until they turn on their Wii next time) and gotten posts deleted off of the Wii Message Board. Nothing of huge significance, but if you do attempt this, I warn you. We still don’t know exactly what it does, and you may be the first to discover a nasty side effect of doing this.
Oh, but of course, how do you do it? Well, when you turn on your Wii, at the Health and Safety screen, hold down + and - and then hold down A and there you go. It’s probably just used by Nintendo when they repair your Wii or something when you send it in, but it’s still an interesting thing to know about. I don’t suggest doing it, but if you do, it’s your choice. There’s nothing to gain from doing it right now, so there’s no point. It’s just like that secret DS button, which doesn’t do anything for your DS either."
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Oh, but of course, how do you do it? Well, when you turn on your Wii, at the Health and Safety screen, hold down + and - and then hold down A and there you go. It’s probably just used by Nintendo when they repair your Wii or something when you send it in, but it’s still an interesting thing to know about. I don’t suggest doing it, but if you do, it’s your choice. There’s nothing to gain from doing it right now, so there’s no point. It’s just like that secret DS button, which doesn’t do anything for your DS either."
Follow link for a video too
Link