SCSI error codes ense keys consists of multiple levels.

Sense key 04hex means what you know already - "hardware error". This is not a NW message.

You should now contact you HW dealer to narrow down the failing part.

There is some issue with you robotic arm check if it is stuck perhaps a tape stuck on it or a=if anything inside the library is obstructing the movement of the robotic arm. if none of above is found you could try rebooting the tape library ans see if that helps.

If nothing seems to be fixing it then contact you hardware service provider.