MacBook Pro keeps shutting down

My MacBook Pro Retina 2015 keeps shutting down every time I turn it on. It happened a while ago and I called apple support up and they sort of fixed it by telling me to reset something. But it's happened again. It started when I was just using my Mac and then a window popped up saying 'are you sure you want to shut down' and I am 100% sure I didn't click shutdown. I them click cancel and it just shuts down anyway. It happened a few times after that and now even when I power it up it gets to about a quarter of the way through the loading bar with the apple logo above it and then just shuts off. Could someone please help me.

Cheers

 

I will, but can't go until Monday as I'm working all weekend so was wondering if anyone knew of how to fix this.

 

Would this be covered by my apple care because I only bought my Mac about a month and a half ago?