Thankyou very much, BEagle! I was waiting for this one! It was a very interesting thing to see the damage and the following repair job - the few photos that captured this.
In short, the summary concludes that Li-battery thermal runaway in a faulty ELT and slow burning resin from the composite materials contributed to the damage.
I wonder why Li-batteries aren't banned on aeroplanes. There is always the "WHAT IF..." factor with those things. I read the report from the 747 cargo flight downed by Li batteries.. extremely unsettling reading. Thank Gods there was noone on board this plane!