Well it's above 90 degrees F now and the humidity has been high in typically dry Dallas area.
I left the PP in for a couple of days. It was encrusted to the surfaces.
I scraped as much as I could with a small paintbrush. The plastic surfaces are ruined, but I was able to use it. I all of it out but the surfaces are no longer smooth and they are stained, making it more difficult to determine if I emptied all the powder out.
Lessons learned.