hmm if you look at the offical Nintendo Forums you must simply unplug everything from your wii for about 2-3 hrs also unplug the power supply so it's not plugged into the wall or the wii. I had to do this seeing as the 1st 3years i didnt really play my wii. Also when installing a Safe Updater befor i knew how bad they were i had a power outage and i had the same result wii would not turn on but when connected to my power tool it showed it was not dead. This is just a safety feature that ninty added.
If you look at you power cord you see that big block in the middle? well that's basicly a surge protector in a way if you get a power outage that block shuts off the rest of the wii so you dont damage it.
Turning your wii off for a day???? well like i said 2-3 hours is what is on the Offical Nintendo Forums and i have done that as well so your pick, 1day or 2-3 hours......... you can see for yourself if it doesnt turn on.