It looks like the error code is 007-2001. Even if I end up not being able to resolve this, I'm not too worried about it--especially with the eshop closing soon for the 3DS. (I'm not sure if that will extend to updating games or not though? Will we still be able to do that once the eshop closes?)
Apart from that, everything has worked great. I just tested out Smash Bros earlier and it works now! I was a little worried at first because it was taking so long to boot, but I guess that's just the slower processing speed of the 2DS.
Thanks again for the help!