Apple - How can I fix Error: -69877: Couldn't open device after interrupted formatting process?

For anyone else who ends up on this question after searching online, be sure that you confirm that your SD card is not mounted as read-only! There is a physical tab that you may need to move:

I have run across something similar before and what I did was issue the command:

diskutil unmountDisk /dev/diskxx

What you do when you shutdown and reboot, even in safe mode is you first unmount all your disks.