laptop keeps shutting itself down and won't respond to power button

MacBook Pro only turns on when I open it it doesn't respond to the power button, when I open it and it turns on I type in my password and a message appears that tells me i turned off my laptop because of a problem and gives me option to reopen the apps.

If I then get in (if it hasn't shut itself down already) it will last about 20 seconds before it pops up asking me if I'm sure I want to power off, I wouldn't of touched anything but before I can even go to click cancel it will shut off and won't turn back on again, which will start the whole process over, if I don't close the lid and reopen it, it will stay off as it will still not respond to power button at this point I've tried holding the power button for different periods of time but nothing happens?