(maybe it's worthless but...)
Here is a movie of the mecanism / motorization (triceratops).
And here are some pictures to show how to open this toy.
WARNING !!! You have about 90% probability to break some plastic parts by opening if (especially the tail). Do it at your own risk (I would say DON'T do it...)
And note that by opening this toy, it will slightly damage the painting, because this toy is painted once the two parts are clipsed.
Unscrew the two screws, remove the head...

Beware, separating the two parts !!! The plastic is glued.

Below, it was nearly a disaster (see the tail, the plastic began to crack).

You can use metallic parts (here the back of a fork) to separate the two parts.

Now the back can be removed easily:

It's hard to remove the belly. I think the legs are factory clipsed at the end of production. I hardly removed the belly by "twisting" it...

The belly part:

The back part. 2 screws and 13 plots are located.
* I meant "toy's belly" not "bully"...