Here is my version of Chappie.
There are two texture files : 4K and 2K
I wanted a great amount of details to get a realistic image. You'll find 13 groups in the fbx and maya files, each group has his own textures. The obj file is just one group, no textures.
The mesh is not rigged but it's not very complex. You can do that very quickly if you know how to.
If you're a Redshift user, the materials are in the maya file. It's PBR, you can reproduce a very similar render with every renderer quickly. In regards to mesh lights (eyes, battery screen, etc), you must look at your own renderer functions ; I researched redshift mesh light on google in order to do this. If you have any questions or problems, send me a message.
Just associate a material with the right group > Color/roughness/metallic/normal
Concerning the lighting, you can get a very nice image with a hdri or area lights around the mesh.