Firmware shouldn’t cause any issue as it should enhance its functionality. That being said, you may try reloading the firmware. Do the manual update
I my not sure if this will work but you can try. While the card is out, turn on the sansa and switch it to MSC mode (Settings > System Settings > USB > MSC). Turn off the Sansa, insert the card and connect it the computer. It should now be recognized as two drivers. See if you can format the card by right clicking on the drive of the card and select format. If that doesn’t work, try to use card reader to format the microsd card.
