Some solutions that may work include:
1. put in a camera and let that try to format the card
2. put in Windows PC and do a low-level format
http
/hddguru.com/software/HDD-LLF-Low-Level-Format-Tool/
I have used the above, FREE version, several times. I've restored many bricked USB thumb drives and there's a pretty good chance it can fix SD cards as well.