I followed your steps but at step 5 it said disc must be reformatted to file E.
Everything we have read says that will delete all info on sd card.
Reformatting will delete what's stored, but if it wasn't formatted FAT or NTFS, I don't see how the data was there to begin with.
1.). How sure are you that you got the data backed up from the Humminbird unit to the card?
2.). Make sure that the card is not "locked"
Depending on where you are, there might be someone out there that will transfer the data for you...