IDK about the punk battery door. I briefly owned the 2 battery punk and the door was fine no latching problems and different design.
The steampunk nano 120 watt mod which I otherwise love had a door issue. I put a silicone sleeve on mine and that held things together. I have heard other successful methods including duct tape and a small ring of nail polish remover to get the door to latch.
I have no clue about the punk 85 watt mod other than it's a steampunk design so it may have a fatal flaw, that is sort of a prerequisite for steampunk design.
I'm mostly kidding on the steampunk ,warrant it maybe? Don't think it's a common issue for that mod.
Anna