For the update process, are you using an sdhc that is either 4gb or smaller?
The SC DS2 and SC Ds(i) mini will only allow updating from a chip either 4gb or smaller. (not sure why this is so..) using a larger cart will not allow the update process to work. You can use a larger card for the actual day to day use, but not for updating. This one had me goin' for weeks. Try that first, once you know you have all the correct software, firmware etc.. in place. Hope this helps.
Micro SDHC class 2 4gb, so... I should try with a 2gb? or this one works?, I've updated before with this one, and the update runs normally on the ds lite but it makes me shut down the 3ds after the update...






