Water coming out of the brew head without brew buttom pushed.

If the pump is running but the coffee button isn't pressed, then the steam knob switch is probably being triggered. Try closing the knob as far as you can and see if that stops the pump. If not you'll need to take the top off of the machine and figure out how the pump is getting voltage.

If the pump is not running but water is leaking out of the group head, the group head valve is damaged or worn out and will need to be serviced. You can find instructions on how to do that in other questions or the teardown of the Barista.