Yes - you should be able to turn the extruder by hand when it is unplugged and therefore not powered.

The V2 comes with a blue plastic knob for this purpose, it may be too small to turn the shaft by hand.  

When powered and "steppers enabled" the motors need a lot more force to overcome, but even that can be done by hand or a machine crash.

If you can't turn the extruder at all, its probably toast.   That you've tested other ports on the board is excellent problem solving.   

Whatever damaged the motor has likely damaged the board too, or vise versa.

You likely need both parts replaced to get this printer working again.   Could be expensive - you might want to compare cost of parts with cost of a new printer, remembering there may be other non-functional components still undiscovered.

Plausibly, with a dead extruder, you could slap a laser on this unit and make it a dedicated burner.  The creality laser module is around $50 USD.