That almost sounds as if your Libra 2's internal µSD card has reached it's end of life and has gone into read-only mode. You may want to try opening your Libra 2, removing the µSD card and making an image from it. You can then re-image a new µSD card from that image. If that doesn't work, you can request an image for a Libra 2 in the
Kobo µSD Card Image Requests thread.