Aura Pro X SSD upgrade for MacBook Pro Mid 2014 issue
I got a replacement hard disk, and ran it through all diagnostics including the apple system diagnostics. It passed everything except the default Apple Diagnostics with the error -  'VDH002 - There may be issues with storage' error. 

So it looks like Apple Diagnostircs doesn’t recognize the OWC hard disk as good for some reason.

Hope this helps someone else!