electric shears just suddenly stopped?

my J.C.B.24 inch blade hedging shears suddenly came to a stop, it wasnt under pressure only cutting a very light hedge. opened it up cant see any visable sign of a blockage or damage. press the switch to the motor and it just makes a noise. put a screwdriver in the sprocket and turn. & it makes the blades move. dont want to go any futher at this stage . dont want to do any damage. HELP PLEASE !