Spaceship BattleCruiser Free low-poly 3D model

While the modell is basically very good, the supplied obj file has severe errors. The sixfold round funnels left and right of the bridge import into blender in a garbled way. This screws up the surface. Additionally, the obj file has the inside-out problem with many panels, making it difficult to apply procedural shaders. Maybe the Maya files don't have the errors, but who can afford Maya? So, please, fix the obj file. It needs to import into blender with outsides out and insides in, all normals intact, and no garbled polygons. Addendum: Meanwhile the seller contacted me, pointing out how to fix the issue in Maya (remove an animation Blender does not understand). However, instead of fixing it for me and sending me the updated obj file, he suggested I do it myself with a trial of Maya. He then closed his message with "Please remove the negative rating you unappreciative brat". Let potential buyers decide whether they'd like to do business with that kind of person.