- Double-click Disk Utility in the
/Applications/Utilities
folder. - Choose View > Show All Devices.
- In the sidebar, select the storage device you want to erase, then click the Erase button.
- Click the Scheme pop-up menu, then choose Master Boot Record.
- If the Scheme pop-up menu is not available, make sure you selected the storage device you want to erase — it’s at the top of the hierarchy.
- Click the Format pop-up menu, then choose
MS-DOS (FAT)
. - Enter a name for the new partition that does not begin with
3ds
. - Click Erase, then click Done.
- Once the format is complete, copy your data back onto the SD card.