27” Mac only boots to black screen

My late 2015 27” Retina display is only booting to black screen. If it is left unplugged for a day or so it will boot up to the Apple symbol and look like it is trying to update something- it will only load about half way and then bring you to a login screen. After switching to the main user and logging in it will run normal for about 5 mins and then the screen will go black again. You can hear the computer still running and if you hit certain keys it will make sounds. We only have a wireless keyboard at this time and that doesn’t seem to allow you to boot into safe mode.