I did another one today and managed to get it back together far nicer than the first one (I had no idea where to cut). Be neat with your cutting, use a steel rule so the cuts are straight and cut about 2-3mm in from the ridgeline on the sides, and about 6-7mm in from the ridgeline on the ends. I was originally going to wrap the back cover with some carbon look vinyl, but I am happy with the result.
I think the ebay vendor knew that these are faulty, as a, he was very understanding to the problem and offered a replacement very quickly, and b, both units I received had been opened and both units were brand new. (i'm thinking that they had been both tested)
Again, unless you are confident with a multi-meter and applying power to the cells, do not try this.