iPod iPod 5th gen Not Recognized in Disk Mode

Hi guys recently purchased a second hand ipod 5th gen 30gb in hope of fixing it up but have found it to be more difficult than first presumed. I have gotten the device into disk mode and connected it to my pc which then makes the device continue to cycle between the well known sad face and apple icon. I have also just installed a new hard drive which i fought would fix this problem.

All suggestions would be appreciated
Thanks