According to Mentour Pilot and Wikipedia, this was the first crash with hull loss and fatalities since the 787 entered service about 14 years ago, so the plane model seems to have a good safety record. Pilot error is possible, but the captain had thousands of hours of experience. No signs of bird strikes were reported. It's most likely a mechanical failure of some kind, but there are so many redundancies in jet fuel systems I have no idea where the issue could lie. That specific plane was 11 years old, so I guarantee things like maintenance records will be examined in detail.