Hello there and welcome to the WD community.
Have you tried a different computer or perhaps a different power adapter to see if the issue has to do with power? Also you might want to try connecting the unit directly to the power outlet to see if the drive gets more power and spins up correctly.
This link might help you out in case you need to know the correct power usage of the drive so you can test witth a different power adapter:
http://wdc.custhelp.com/app/answers/detail/a_id/1378
Hope this helps you out.
