I had my firelink working after a LONG time. I then was disappointed to find my game files wouldn't save. A friend of mine tried adding a different firmware (Fire Link firmware v1.23o), it then asked to reformat my card yet my computer refused. It said it was unable to. I need help to fix it now because I can't access anything.
Try to format the card with this software: https://www.sdcard.org/downloads/formatter_3/ if still not working, then you may have to get a new SD card.
Far as I know, firelinks are first gen flashcarts, it uses internal-non removeable micro sd. I have one and still in use. So if its dead, its dead.