Laptop won't turn on?

Model: MT6458 Gateway

Monday of last week my computer beeped several times ( I don't know how many times) and then I locked the laptop and everything worked fine afterwards. I have only used my laptop once since then and I went to turn it on and for a few minutes no problem, I had a flashdrive (removed now) in and was on word. But it turned black and the blue light remained on. For a few times it let me try to turn it back on but its stopped and the blue light has gone off. I tried taking out the battery and unplugging it and holding it on for 30sec and then putting it back the way it was and turning it on but this has not worked either. Now everything is off and it will not turn on. The battery is glowing above 50 and alittle bit of 75 so I know its not dead. Is there anything I can do or is my laptop dead? I have had the laptop for three years if that makes a difference