Motor should spin with 12 to the motor terminals.
Try a jumper wire from the blu to a good ground..that takes the reg out of the circuit and will gve the motor a true ground....make sure the key is ON so you have pos power to the red at motor.. this is basically the same as direct battery voltage to the motor, by-passing any controls.
If you have power and it still will not start, give it a spin by hand while the power is applied. Your idea of friction may be very different than mine..the fan should free-wheel when you spin it bt hand.