I don't know what type of epoxy or polyester resins your using however, Putting polyester over epoxy is a no-no. The other way around works if you have "sterlized" the part. ie. sanded with 80 or 100 grit and wiped with acetone
At this point I would get some Acetone or MEK and try to wipe it off as best you can, then put it in an oven, lowest heat possible (125) and bake it for at least 4 hrs to see if the surface will harden.
You will most likly find your epoxy part softened, baking it MAY bring it back to a usable condition.