You'll find 4 models ( 2 solved and 2 unsolved ) :

- Solved_unt : single mesh (1512 verts) 

- Solved_sep : group of single cubes (56 verts)

- Unsolved_unt : single mesh (random rotation)

- Unsolved_sep : group of single cubes (same Unsolved_unt 'rotation)

In the "single cubes" version, all cube are parented to the central cube (the one you can't see).  To clear every parent, selecte all objs and type "Alt+P" and "Clear Parent".

Principled BSDF materials used. Incrase roughness if you want less reflects on faces