Here's how I describe this scenario:
1. An LD3 container (the main type of cargo container used on passenger 747's) is holding a number of passenger luggage bags and is placed very close to the suspect fuel tank.
2. Inside one of the luggage bags in that container is a consumer electronic device (likely stereo boombox or laptop computer) with a shorting battery.
3. The battery in suspect consumer device explodes spectacularly from the short (which can happen due to the explosive and toxic nature of modern battery materials) and sends sparks and shockwaves away from the container towards the suspect fuel tank.
4. As the sparks and shockwave puncture the fuel tank, it ignites the fumes inside the tank like a fuel-air explosive bomb with great force.
5. The force of the explosion is strong enough to rip the fuselage in two as described by the official FAA/NTSB report.
The reason why I mentioned this scenario is that a few days ago a United Airlines airliner that was supposed to fly from San Francisco to Hawaii suffered an unusual explosion inside the cargo hold during passenger loading and injured a ground worker. It was later determined that the explosion was caused by a battery in an electronic device exploding, mostly likely due to it shorting out.