What to do with the cracked paint?

To fix this problem so common need the following elements:
Brush bristles hard
Spatula
Brush plane
Sheet of sandpaper
Gypsum
Cube
Sponge
Painting

If the painting is only flake off, you'll wet the surface and remove the old paint with the spatula. Then clean with a brush.

However, if the layer is very thick, there is a plats with the spatula to equalize.

Upon drying, apply a league fine for not being noticed settlement, and finally painted.