The holes that were drilled revealed that screws were attached from the inner side of the earcup.

There are a few seams to choose, but the one I chose (which is also the correct one) to begin further disassembly is between the foam pad and the small first layer of plastic.

There is no magic that can help this step very much, as heat around the cushion can easily deform or melt the plastic, and heat from the back cannot penetrate the insulating plastic and air from the other side.

Insert a metal or plastic spudger roughly half an inch between and slowly rotate to separate. You should hear the strong adhesive releasing slowly.