Using a official disc update will not resolve a banner brick. But you probably don't have a banner brick, you have a full brick due to a stubbed system ios. Mh, but you said 4.1 ran flawlessly ... what exactly do you mean by that? Have you rebooted your Wii after upgrading? And what wad did you install that may have caused a banner brick? Have you tried getting into recovery mode? AFAIK, recovery mode will not work if there is no system ios. Even if it did work, do you know any game that has a 4.2 update partition? I'm not sure there is one yet. Probably Mario Galaxy 2 will have it.
A wode is only a drive emulator. It will not get you into recovery mode. To get into recovery mode, you need a modded gamecube controller or a savemii dongle. But with a stubbed system ios, it probably won't work anyway.
Define "boot2 CIOS". Did you have "bootmii as boot2" or "bootmii as IOS"?
If you have a complete bootmii nand backup, you may be able to restore it either by getting into bootmii if you had it as boot2 or with an infectus modchip.
Otherwise, your only option is to send it to Nintendo, claim you wanted to make an online update to 4.2 and it was bricked afterwards. If they don't find the homebrew, they'll repair it on guarantee.