I'm new to this too, but some things I already learned.
1) cant access my wii settings --
Semi-bricked!
2) dont know what caused this... i think it was super paper mario --
Updating firmware that is not in your region. NTSC-US updated to PAL-EU, vice versa.
3)if it was super paper mario, this is strange. the site i got the game said it was pal, and it works just fine, but caused my wii to semi brick.
4)obviously,my wii has a modchip (dunno which one) (how do i know which?) --
You have to open up your Wii. I think you will need one of those special screws. 
5)i can still play all the games i have so far but the ones i download (supposed to be PAL) wont work
6)i dunno what firmware i have
7)downloaded "wii-system-menu-update-PAL-v290" but my wii wont play it
it says i have some corrupted files --
Maybe firmware greater than 3.2...
please HELP! --
I also have the same problem. Anyway, from whatI've (we've) read, the easiest way is to wait for a game with a disc update that is greater than the currect firmware installed, of course, must be the correct region. :P
Good luck!