Following this guide to upgrade the 500GB HDD to a 2TB SHDD worked just fine. You'll need to download some script to be able to format the larger HDDs to be able to access the larger available space on the Xbox - YouTube is your friend here.

Reinstalling the OS seemed to be simple enough. Until you realise that the bootanim file is missing. Taking out the HDD is required to put this file on via Windows.

Until Microsoft release a new update, of which the console was unable to update via internet. So I reverted to use a USB flash drive to perform an offline update, which was successful. BUT… the bootanim is again rendered missing. Not too sure if I fancy repeating the tear down again and again after every update. Doubt the clips of the underside of the console can handle such a beating…