My Q-Series will turn on while pressing the green button, but will not stay energized.

Your E-Stop could be active. Check to make sure the E-Stop in the front face of your machine is not engaged. Also, the US 110 volt edition of Q-Series machine has an additional spindle safety circuit to check – Make sure your 110 volt plug from the back of the machine is connected to a live power source, or, your spindle safety override switch (located on the top of the machine) is engaged.