MacBook Pro 2011 Turns off on start up

Hi All

I have a 2011 MacBook Pro.

Running Sierra OS. A few days ago it restarted itself whilst watching a movie but it only makes it to about ¾ of the Bar on loading screen with the apple logo before going black. The apple logo on the back lights up until it goes black.

I have tried resetting the PRAM and SMC. Neither have helped.

I’ve taken the laptop of the power adaptor for a day before retrying.

Have looked on other threads but nothing has worked.

Open to suggestions on what to try as Genius Bar reservations waiting list is a week long.