can engine be "rebuilt" ?

The first step on this type of situation is to evaluate what is the damage of the engine, if the engine get a flash flood from gas & lack up during crank, there is a possibility to have a connecting rod bent,if is a flash flood from water then the engine should be removed from the car an at least the head removed to check pistons strokes at the TDC and possible bent valve in the head, if there are no differences in the pistons heads measurements at TDC then proceed to open the oil pan and clean the engine up inside of the crankcase, clean the engine head and reassemble, in the case that the valves or connecting rod are bent, then estimate how much that will cost and compare to replace the entire engine, and make the wise decision. The N55 engine use a turbo also and has to be evaluated very accurate for damage, specially on the flash flood from water due to sudently temperature change in the exhaust turbo chamber (Is extremely hot at that specific moment)can be cracked and have exhaust leaks & making noises. Strongly suggest to replace transmission oil & filter too.