If you've installed any .nsp, did some hacky/pirate stuff and go online again, a ban is most likely inevitable.
A clean nand could somewhat safe you, if you did your cfw stuff only offline and never connected to WiFi without protection like
90dns or incognito.
It's not the backup which has been blocked or not which lead you to problems. Your serial number will be flagged, doesn't matter if you ran into problems before.
Once you are blocked, you cannot simply restore to a point where you haven't and be safe again. Nintendo would still ban you right away.