We know that part of the Jericho squad (Jones and Cole) was killed, just before the party with the Firstborn started. However the four (five?) remaining members defeated the Firstborn and then swam to escape the collapsing cave (the death of the Firstborn appears to have had some cataclysmic effect on the Box).
Did The Box remain intact and were the Jericho squad trapped inside it with all other previous "sealers"? Did they manage to escape into the real world? What happened to The Box and the other trapped souls? And what happened ultimately to Ross?