If DFT gives (extensive damage) or 0x70 (fatal hardware error), replace the drive.
Hitachi Global Storage Technologies (HGST), now a Western Digital subsidiary, manufactured highly reliable HDDs. However, like all mechanical drives, they can fail due to bad sectors, firmware corruption, PCB issues, or head/media damage. This report covers legitimate repair tools ranging from free diagnostic utilities to professional hardware interfaces. hitachi hdd repair tool