tried to erase a mac drive got could not unmount disk

There is a post with a roughly similar issue here.

Gives: Could not find disk for /dev/disk1 But then repeating: diskutil eraseDisk HFS+ DiskName /dev/disk1 Gets: Forced unmount of disk1 failed: at least one volume could not be unmountedīut then despite that error, the disk has been unmounted - it does not appear in diskutil list. So then: sudo diskutil unmountDisk force /dev/disk1 Or this: diskutil eraseDisk HFS+ DiskName /dev/disk1

Trying this: diskutil eraseDisk ExFAT DiskName /dev/disk1 Since then the disk will now no longer show in Disk Utility, but will show in Terminal, like this: /dev/disk1 (external, physical): I first tried to erase the disk in Disk Utility (HFS+, GUID Partition Map), and got an error, saying could not write to last block.

It is connected externally via a USB to SATA cable - I have tried two different USB to SATA cables that both work with other drives. I have a 2Tb 2.5' hard disk that was formatted for a PC (but had errors), and have now connected it to my Mac.

Tried to erase a mac drive got could not unmount disk