Your textures are not PBR correct, and you are lacking the most important map in the PBR workflow, a gloss map. Everything is monochromatic and really flattens out all that hard work you did with the highpoly.
Piggy backing off of what BARDLER said, everything being monocromatic really hurts this. Might be nice to get some sort of color scheme, where some panels are different colors and such? Having everything be that orange/brown color just isn't working. You need some accent colors or something. Not sure if you are working…