Lap top turn off s, and doesnot turn on

Hello,

I have hp, pavilion dv6. it suddenly turn off and didnt turn on again. Then by chance it got on after a day, and turn off again. I took it for repair, the person took out the batt and charger plug, press on button for few sec and place the batt again. It turn on my lap top. Now again my lap top went off after 3 days, i tried the same thing but its not turning on. I want to know that why its doing the same thing again and again.