I've read elsewhere that this is the 8th time a FADEC engine has failed to shut down (or respond to commands to shut down) during an incident. Basically the engine control electronics tries to keep the engine going in the last commanded state in the event of lost coms. In the QF1 Singapore A380 event, it took the fire brigade 3 hours to eventuallly 'drown' the engine in water/foam before it stopped.
There is now some doubt about the evacuation timings. There is onboard video of PAX in the rear cabin running forwards through empty front cabins as the fire brigade foam the wing/engine/fuselage areas. Initial reports were that the first fire appliance arrived about 6 minutes after the plane stopped. If that's correct it's far too long - The last survivor from the Manchester 737 was carried out (by a fireman) at about 5:37 from the alarm being raised. My understanding is/was that airport fire services are supposed to reach the scene of an on-airport incident in 3 minutes.
Also AIUI the CVR and ADR have not yet been found. Another problem with letting the aircraft burn to the ground. They are very very rugged devices, but may not survive 5-6 hours in an intense fire. Worrying.