No one knows why it crashed, but maintenance issues are unlikely. The fact is air crew should be able to diagnose and contain "normal failures". Memory items address time critical issues and the QRH is the shortest form of actions prescribed by the manufacturer. Statistically only a very small percentage of crashes are not caused by pilot error, albeit by compounding the situation by taking actions outside of the recommended or failing to diagnose the issue correctly and doing the completely wrong actions for the phase of flight. Sounds harsh, but this will be a "pilot error".