HyCu looks like some weird chemical formula. It is pronounced either "haiku" or "hi sue", both of which don't sound very appealing to me.
I don't think the connection between ED / DragonBox and HyCu is very convincing. Yes, a box is a kind of cube and HyCu stands for hypercube, which is a cube in more than 3 dimensions. Still not a very strong connection.
The connection between Pandora and HyCu is even less convincing - yes, in the myth there's Pandora's jar, which was typically mistranslated as Pandora's box, and a box is a kind of cube and HyCu stands for hypercube.
I wouldn't focus too much on boxes and cubes - there's already the XBox and the GameCube, it does not feel very original to add the HyperCube to that list. Everyone would call it the HypeCube by the way.
Anyway, a name is just a name, we can probably discuss about it for years, but in the end some decision has to be made. Not everyone will be happy with that decision, but life will go on.