Can you give a little more info please?
I understand the wii was never softmodded, how about hardmodded (modchip)?
Did you try cleaning the disc? Fingerprints and dust can quickly make a disc unreadable. (Just use a dry cloth to clean it, your shirt should work fine)
Are there any scratches on the disc? If there are, try removing them with a polishing compound.
And do you get any kind of error ("The disc could not be read, please remove the disc and turn off your wii." or something like that)?
Do you just get a black screen?
Or does the game load, but freeze or give a disc read error at some point?
And lastly, is this before or after putting the hacked save (I understand you're trying to use the smash stack exploit) on the wii?
Try removing that save and check what it does if you put it on first.
If all else fails, contact nintendo's customer support saying that the game doesn't work anymore after updating to the latest system menu.
Say you've never made any modifications to the system when they ask for that, as you didn't (yet).
If they tell you to send it to nintendo, make sure you still have warranty. Also, don't send it in if the wii was ever soft or hardmodded as they can see that even if it's removed and they will ask you insane amounts of money to remove it (or they refuse to repair it).