So,i wanna ask is there the motor will become short circuit?
Any well designed motor will have a very low impedance with a locked rotor. Low impedance means high current and much power. Locking the rotor is never a very good idea. Try to understand the concept of back EMF.
Opening a switch means switching it off. If you make switch on with rotor blocked, it will over heat and burn in minutes.
It depends on what you mean by opening the power supply. If you mean switching it on, yes, there is a good chance that you will burn out the motor. It does not sound a very useful thing to do.
Yes , the motor would become short circuited.
