Mac Book Wont Turn on

[Generic81]

hi iv just got my self a 2008 13" mac book had it about 4 days now and its been fine up till now i was just browsing the internet when it just turned off there was over half the battery left aswell when it died i tryed turning it back on and it wont turn on the hdd indicator light comes on then powers off its making the sounds off it trying to load but turns off after about 2 seconds once the power button is pressed just wondered if anyone knows whats up with it ....thx