Try to reinitialise the WD external HDD to the factory condition.
Download the Windows executable (requires no installation) version HDDGURU: HDD LLF Low Level Format Tool
, run it with your ext. hard drive plugged in, select it and do the low level format. This may take a few hours. ( I see that you have not tried diskpart - clean all. This software does the samething - writing zeroes to each and every sector and reinitialising the hard disk drive. One advantage here when compared to diskpart-clean all is that you get a visual representation of the progress and you will not get impatient.)
If it enconters errors, that will appear in the dialog box. In that case you have to fall back upon the drive manufacturer's test/diagnose/repair utility and check the drive.
If it successfully completes the LLF, you have to carry out a regular format.