Need guidance on replacing a failed HDD on MD3200i.

Nee to replace a failed HDD, trying to initialize it via the DMDM but all options are greyed out. Disk Guru marked it as by-passed.

Replaced failed DELL 4TB with WD4TB - R/W speeds are the same. 

Is any work required on HDD before slotting into MD3200i? I'm probably not following procedure correctly - can someone advise please? 

 

Thank You.