CAREfully sand back till you've come to where the
paint is sticking well. Hopefully, you still have some of the original paint you used. Once you've got a clean surface, fair the edge. Clean thoroughly with acetone. Prime, and re-coat. If it's only 1 cm by 1cm, you'll probably
wind up with about 3 x 3 to re-paint, by the time you've sanded back to well-stuck paint. If you try to pry it up with a screw driver, you will chip off more than you need, so don't get tempted, ......and pls., don't ask! ;-)
Ann