HP laptop powers on but doesnt start up

HP laptop powers on but doesnt start up

When I press the power button the quickplay buttons light up and it sounds like the computer is starting but before the HP screen shows it powers back down. It will keep cycling on and off unless I press the power button and turn it off. I usually wait a few seconds and try again. Sometimes it starts easily and other times it can take 15 minutes or more to get it to start up. How should I fix this?