so, a follow-up. i got my wii back from nintendo, of course, they sent a completely different refurb. case is scuffed up a lot more than my old one. got it with 3.3U on it. updated to 4.1, backed up my sd card and formatted it. went to work on hacking, banner bomb, and somewhere between bootmii, patching IOS36, preloader, and installing cIOS38, the system files got corrupted. i use the windows commandline often, and during the above i'd noticed some "The parameter is incorrect" errors on the SD card when doing a dir on root.
before backing up the card, between almost every entry was a "The parameter is incorrect" error. i think my sd card was on it's way out, the reason why the nand/restore backup was useless and ended up bricking it in the first place. it was a Dane-Elec 2GB and probably about a year and a half old.
i could still get into BootMii and HBC, so I ran AnyRegionChanger and rolled it back to 3.2U. works. redid the hacks from scratch and everything's fine now.
bought a new sandisk 2GB today and re-backed up the NAND.
I guess it IS true, BootMii may be picky with it's media, but another major thing to watch out for is using older, possibly failing media. thought it might help to emphasize it to others who might come across the thread.
thanks for the help all, again. going to update to 4.1 again soon and hope i won't need to be back for more help.