If the blender is not correctly assembled, then the built-in safety lock may not be released/unlocked and it will not work.
To assemble the blender correctly, please follow these steps:
1) Turn the blade unit on the blender jar.
2) Place the blender jar on the motor unit and turn it clockwise to fix it.
3) When the jar is correctly fixed, you will feel or hear a click. Then the built-in safety lock is unlocked.