I injected a banned Friend_code_B into an unbanned unit (because my unbanned unit is expendable), and it got banned. (proves that friend_code_B is the problem)
Reinjecting the unbanned Friend_code_B unbanned it. (no surprises there)
Transfer is across O3DSXL US and N3DSLL JP
So now transferring the unbanned friendcode to the originally banned unit, and its unbanned (the 002-0102 code gone)
However, can't access eshop (022-2812).
(edit: after accessing eshop, funny enough, I can still access online services)