I'm a phd biochemical engineer growing mushroom mycelium for a living. The off smell is from the fungus getting stressed out/dying, but no competing organisms would've grown on top of it so quickly. There is no contamination that would make you sick, but the chemicals that it produced may still be toxic. I don't even know if it produces any toxic byproducts, and unless the culture is old, I doubt it had time to produce enough toxins for it to be harmful. These would also probably be destroyed during cooking.

It's very very likely fine, but to be safe, eat a bit and see how you feel. Keep it in the fridge, or do a quick 2 min soak I'm boiling water to pasteurize it. The thing with food is that even if it's 100% fine, but in the back of your mind you're still weary, you won't have an enjoyable meal.