What kind of spary did you use????
For circuit boards, the topcoat spray is for soldermasking and
dielectric coating, and has some pretty aggresive solvents that may
react with acrylics, or worse, the polystyrene of your car body.
Like was said above, you may need to strip with oven cleaner, prime,
and repaint, and use an acrylic topcoat. A safe rattle can spray
type is the kind that flourists and artists use to topcoat flower
arrangements and paintings. It comes in both satin and gloss and
can be found in the craft and art supplies departments of most large
retailers.
Scott