After the ship capsized, the engines (and generators) could not have continued to run inverted due to lubrication and fuel delivery problems. Engines can not run upside down as they will fail due to lack of lubricant, since the pickups are at the bottom. Same for fuel - most fuel pickups are near the bottom of the tank so you can use the full capacity of the tank. With the ship upside down these pickups would fail. Even if battery power could run some emergency lights for a while, there would have been nothing to supply the massive energy needed to run the bow thrusters.
The opening shot of the film is the most expensive shot ever produced using CGI, costing at around $2.5million.