Flinter is found at the end of the mission, "Splinter Group". He can be spawned by lighting up five green lights located above a DAHL chest found just after the room where the quest is completed. There are four objects in the room that change the lights from red to green. These include a floor switch, a wall switch, a TV, and a valve. Once all five lights have been lit green he crawls out of the wall to the right of the lights, attacking the player(s).