I hate to be the bearer of bad news but the Kobo N514 Aura does not have a removable internal µSD card.
There is a possibility that you can boot from a µSD card with the Kobo N250 Aura H2O image in the external µSD card slot and restore operation that way. See
message #124 in the
Kobo µSD Card Image Requests thread in the Kobo Developer's Corner forum.