Ps4 won't start after update

So I have an original ps4 500gb model. And for some reason when I turn it on it won't stay on for long. It will randomly shut off. I'm trying to update it because It didn't have a hard drive. So after some time i finally got it to stay on. But everytime i reinstall software it will reinstall then say prepare to update then it will turn off and say cannot start ps4. So again I'll try to reinstall software it will reinstall update. Then when it says preparing update it will shut off and turn back on saying cannot start ps4. So after awhile finally got it to work. But it goes to playstation logo screen hangs there for 1 minute or 2. Shuts off and goes back to saying cannot start ps4 system. Any ideas? Am I doomed. Already swapped power supplies. Still did the same thing. Swapped hard drive with a new one. Same thing