How to diagnose HP zv5000 start up issues?

I have a HP zv5000 with an AMD processor that does not boot up (Windows XP). When I press the IO button, the fans on the machine come on real high and nothing else seems to happen (no picture, the IO LED does not come on but the wireless LED, speaker LED do come on). The fan keeps going at the same high speed for ever and nothing comes on the screen?