(1) use the cutting pliers to cut the cable where it was broken, so you can easily manipulate the case

(2) use a knife and some alcohol and cut through the seam of the case until you can fully release it. ( I haven't tried with heat, but it might be helpful too)

this step requires force and patience. the case is glued very tightly.

be mindful of what's inside (see pic) so that you don't damage anything. while this is highly unlikely due to the thin metallic shield, be careful. Despite this unrepairable design, you want to be able to put it back together in a working condition