For starters I would try it on another outlet that you know to be good (test it with another device), and if you have it on a GFCI outlet then make sure it isn't tripping the breaker.
If you've verified the power source if fine, after turning the machine on and waiting 5-10 minutes, do you feel any heat coming from the top of the machine or the brew head? Does the green "ready" light come on?
If so, but pushing the brew button doesn't do anything, then you could have a bad brew button or a seized pump.
If you don't feel any heat then you probably have a ruptured heating element. If the machine sat for a long time with water in the boiler then scale buildup on the heating element was most likely the cause of this.