To fix broken low poly 3D models, first identify issues (non-manifold edges, overlapping vertices, missing faces) with your software’s inspection tools, then use repair features like merging vertices, filling holes, or recalculating normals.
Non-manifold edges (edges with too many/few adjacent faces) or loose vertices cause most breaks—use Blender’s "Select Non-Manifold" or Maya’s "Check Geometry" to find them, then merge or delete redundant parts. For missing faces, use "Fill Hole" or "Bridge Edge Loops" to close gaps. Recalculating normals fixes invisible surfaces by aligning face directions.
If problems persist, retopologize to rebuild clean low poly topology—this resolves underlying issues while keeping the model simple.