Why does my Apple laptops turns on and shuts down within second?

My cousin gave me a used MacBook pro and when we try to turn it on it has a spinning circle under the apple logo. Within 5-6 seconds it shut down on it own and turn back on its own, and keeps repeating the process again and again. I tried the trick that I have found online and the only one that responds is pressing the power button and control button. It takes me to a picture of a hardrive. It said Macintosh HD, it only has that one. What do I do next? What is wrong with the laptop? Is their a Fix?