You may want to get a couple of new SD cards first. One for use and another as a spare. Best kind are the High Endurance that will tolerate many read and write cycles, something that is continuously on-going with your scanner. Then follow these steps for both cards (best if you do it in a computer's card reader as it goes faster):
1. Format the cards using the SD formatter utility and note which Drive letter is associated with the cards. See:
https://www.sdcard.org/downloads/formatter_4/
2. Use Sentinel and do a Clear User Data function. (Top row of Sentinel under Scanner). Check the box that says Display all drives, then select the drive you noted in previous step. Click OK. This writes needed system files on the new card.
3. Click on Scanner again and do a Write to Scanner, including Force Write Full Database. (Usual process to write to a scanner that you've done before).
4. Unmount or Eject the SD card and repeat steps 2-4 for the second card.
Both should be ready to go.