I would first make sure the steam wand tip isn't clogged, as that's the only thing that can prevent water from dispensing from the wand if the pump is indeed running and creating pressure. If you can't get any water to dispense you won't be able to descale the machine, as that requires getting the descaler inside the boiler. You may also want to try taking off the group head screen and removing the boiler valve retaining nut, spring and nipple; water should be able to flow from the boiler then. If not, it's possible the pump isn't working, despite making noise.