Well I opened the unit up very easily - with of course a 2.5mm allen key for the front and a universal tool to help with the top. The universal tool was much more suited to this job than a screwdriver. In case anyone wants to know what the universale tool is: they're the metal back plates used to cover the slots on the back of your computer when you don't have a card in.

Anyway, there was no warranty seal on the top. There are two warranty seals on either side of the drive mounting plate though.

And Archeon is correct. The drive cable is under the drive tray and can't be seen without moving the tray. Moving the tray would break the seals.

I have written back to support asking them if I can have special consideration in this instance to take a look and then return the unit if there is nothing wrong with the cable. If it's only the cable, I would really not like to go through a week of downtime making arrangements to send this unit back and then waiting for a replacement - meanwhile my car is being driven around with half my dashboard missing. :)

Thanks for all your help guys.