If your mushrooms and the mycelium are covered with a black/purple powder, your shrooms have sprouted spores. In this case, your harvest was a little too late.
This happens to the best of us, but what now?
Are my magic mushrooms still edible?
Yes, you may still eat them. They may have lost a little potency, but usually not that much.
Is my kit still okay? Can I go for another flush?
Your growkit is contaminated with spores. The spores and mycelium work against each other. The spores will look for a place to germinate. In nature, this can take up to a year. The mycelium in the box is disabled by the spores and won’t produce any more shrooms. You can only get another flush on the spots that are free of spores.