I'm not convinced that the extent of damage to the engines is relevant. It seems clear from all reports that they were both running (i.e. burning and turning) before the incident started. The aircraft continued to move forward at 100+kts until it finally reached the ground. Even if the engines had both flamed out when the thrust loss occurred, they would still have been windmilling fast enough to wreck the fans on impact.
The damage says they were both turning. It says nothing about whether they were burning, and if not, when the flame went out.