If you format the Wii that has homebrew on it, can I go online and update without a problem?

If you format the Wii that has homebrew on it, can I go online and update without a problem?

I didn’t mod the Wii, I bought a homebrew wii on craigslist and didn’t know about this crap till now.
also is it a good idea to format a pre owned Xbox 360, to prevent being banned would that help at all, does formatting get rid of mods