Aren't all the high voltage components and wiring outside of the passenger compartment? While it's possible it could have started outside the car, then spread inside (happens all the time with ICEVs), I'm wondering if this isn't just a run-of-the-mill 12 volt short from behind the dash.
Blue Ocean 2012 Leaf SV, lost that 1st bar at 34 months/26,435 miles. Lease returned 2 months later. Final LeafStat figures: 225 Gids, 17.44 kWH, SOC 91.89%, SOH 82.36%, 69.49% HX, 54.57 Ahr, battery temp 61.8 F.
Now driving a 2015 VW eGolf SEL.