So one of those scented oil plugin came loose from an old outlet receptacle and the spilled oil messed up the floor finish. I didn't notice for a bit since it's behind a table (you can see the circle where the oil pooled around the table leg.)
I'm not sure what type of stain the floor already had but I have a feeling it's an oil-based one. Anyhow I cleaned the oil from the area with some water and bit of dish soap. I also tried lightly sanding with a 120 grit paper, and tried this Minwax PolyShade stain+poly-in-one product, but the stain didn't seem to penetrate at all. Perhaps it was water-based?
How do I go about fixing this correctly? I don't know much about wood staining...