iPad smart folio stains

I accidentally spilled a small amount of hand cleaner on the back of my new iPad Folio keyboard/case. It dried before I noticed it. I have tried cleaning with a damp cloth as recommended but the stains remain unchanged. I am very disappointed in the quality of this case, it seems that apple sacrificed function for appearance in materials and it doesn’t resist what would be normal use in my opinion. Anyone else have any ideas on getting the surface back to like new?