my presario f700 will not turn on, when i press the power button all that happens is the blue light comes on but after 0ne second it turns off, but,sometimes the light stays on for like 20 or 30 seconds then shuts off, i hear the fan turning on just fine but no screen lighting or anything, its been doing this for about 2 months but, the last 4 times it happend i just sat it aside for like an hour or two, than clicked it on then it worked perfectly, but now its been 3 days and nouthing,

please help, cause im a musician and its really important that i get it running,