Did you enable “Generate overlap components”? Or try with “other actor” or “other component”? I never made a boxing game to be honest, but I would check that first i think.
If the body is still playing animations from punches then in your character blueprint you need to create a variable for the death state. I have one in my blueprint called IsDead. Then, when you take damage, only allow further action with a branch node if you are not dead.