Need Help On Un-deforming A Mask

[🪦 killnskin ●]

I just reseved this mask today from Biomorphs, and the paint job is awsome the sculpture is incredible but sence they somewhat mass produce these masks they keep them stored untill there get sold and shipped ,so now it has a fold down through the middle of it near the seam and as you can see form these pics the front neck is all messed up. does anyone have any ideas on how to fix this? Also, im ONLY asking those who have actuily fixed a mask in a similar situation. please no speculaters. Thanks!