for anyone else:
I just recently popped my Cube amp open as well. It seems like it's just glued shut, but it's not a chemical glue so you should be able to pop it open with minimal difficulty. I used a piece of sheet metal about the thickness of a razor blade, so a razor blade itself would probably work to open it up.
[image|1045220]
Just be careful because the bottom half has a groove that the top half actually fits into; you can't just slice a razor straight down because it will hit the bump.
[image|1045221]