There are a bunch of deformers in that area which makes using other ones, like magnets, problematic.

You can do it by first exporting the chest as a wavefront.obj, taking all the appropriate precautions for creating morph targets (IF you don't know what those are, reply and let me know.), and then import it back into a scene and muck about with it with some magnets, making sure to not change the object's location/rotation/scale while you're working on those areas. Once you have them looking as you'd like, then spawn a Morph Target for the object. Check to be sure it looks as you want it to by zero'ing out the magnets and with it's value set to 1 Export the object, with the morph target you created set to 1, once you're through, then load it as a morph target for your character.