Coming from a very good source, there is no indication nor evidence to show that there were nefarious activities behind this. Sometimes, an accident is just that: and accident.
They are looking into the fuel of the ship (was it bad fuel which then in turn shut the engines and power off and the black smoke after the power came back on. Think of your lawn mower with bad gas. It just shuts down), they are looking into the ship itself and the electrical system, they are looking into everything.