WD ELEMENTS TB3 not reformatting

Bought a brand new external hard disk WD elements. As i am using a an iMac i tried to reformat it to a mac readable and writeable disk. It kept failing to reformat, and is somehow deactivated. It does not show up in the finder. Now I am doing a slower erase but it is taking forever. How can I get this disk to work? Or should I return it to the shop as faulty ?

You should follow this KBA to reformat drive in macOS:

https://support.wdc.com/knowledgebase/answer.aspx?ID=20791#highsierra