Follow the instructions on Page 81 of the User Manual:
Reformatting the microSD Card
Reformat microSD cards using a special SD Card Formatter (https://www.sdcard.org/downloads/formatter_4/). (Note which Drive letter is associated with the SD card)
Then, you need to “Clear User Data” using Sentinel to restore all HP files and
directories to the card. (Check the Display all drives box at the bottom of the window, then click on the Drive letter associated with the SD card. Click OK).
Lastly, do a Write to scanner to add the full database, Profile and Favorites Lists.
SD cards go bad. Judging by some posts I've seen, many users have upgraded to larger cards anyway. And if it was me, since they are fairly inexpensive, I'd get a second and set it up, just to have as a spare. (If you have a 536, I've seen a suggestion to tape the spare on the bottom of the scanner, which I thought was a good idea.)