Software failure on Mybook 2TB. HDD & NAS board ok. How do I reinstate the disk?

Been perfectly happy with the Mybook 2tb, until I had a power cut. I have two of these devices and now only one works. The other has been taken apart and the hard drive inside has been tested and is running well, although the NAS software is no longer on there. I have had to format the disk (linux) to get it to be readable again.

The Mybook mainboard has been tested in my other Mybook and this is also working fine.

How do I get the Mybook software back onto the HDD? Is there an image I can copy over to this disk to enable it again, or can the device be placed on the network and TFTP’d up to it?

Hey! someone must know how?!