If an update could fix your Wii then you'd need New Super Mario Bros which is about the only game that has 4.1 so far, apart from a few Japanese games. However inserting a 4.1 disc would only fix a semi-brick, which you probably do not have. WiifitPlus does not have 4.0.
You didn't mention what caused your brick so I'm assuming it a Banner brick seeing as you say you have some Wads ready.
If you have Health and Safety screen you can try maintenanance mode, hold - and + and stab at A a few times. You should be able to launch Wad manager from there.
If you have bootmii/boot2 you can launch HBC and Wad manager through a few different techniques.
There's a few Unbrick discs in my mediafire http://www.mediafire.com/?sharekey=b...eada0a1ae8665a