First Aid not working on WD My Passport for Mac.

Hello barneyhairball,

If the First Aid process is unable to repair the disk then it could mean there is some sort of unrepairable issue with the formatting/file system or it could mean that there's an actual hardware issue with the hard drive.

You can try reformatting the hard drive to see if that gets it working.

1. Open the Disk Utility app on your Mac using one of the following methods, depending on the type of disk or volume you want to erase:

• If you want to erase your startup disk: Start up your computer in macOS Recovery, then choose Disk Utility in the Recovery app. To learn how to start up your computer in macOS Recovery, see Intro to macOS Recovery.

• If you want to erase any other type of storage device: Double-click Disk Utility in the /Applications/Utilities folder.

2. Choose View > Show All Devices.

3. In the sidebar, select the storage device you want to erase, then click the Erase button .

4. Click the Scheme pop-up menu, then choose GUID Partition Map.

If the Scheme pop-up menu isn’t available, make sure you selected the storage device you want to erase—it’s at the top of the hierarchy.

5. Click the Format pop-up menu, then choose a file system format.

6. Enter a name.

7. (Optional) If available, click Security Options, use the slider to choose how many times to write over the erased data, then click OK.

Secure erase options are available only for some types of storage devices. If the Security Options button is not available, Disk Utility cannot perform a secure erase on the storage device.

8. Click Erase, then click Done.

Erase and reformat a storage device in Disk Utility on Mac

If it's still not working after that, then that would indicate the issue is hardware based. At that point you'd want to contact the manufacturer of the hard drive for repair or replacement options or look into buying a new one.

Cheers!