Painting on metal, offering advice

[Марина13]

Fragment of painting "Last Supper" done on zinc butter in a side light. Most likely this is a piece of the iconostasis. Across the surface of strong deformation on the mechanical effects of a sharp object on the reverse side. Paint in these places was preserved. I need advice as to align the deformation without damaging the paint layer. If someone faced with the - help, I will be grateful))))