2015 Imac wont boot

[g.t. rags]

So I was in the process of doing a software update, and I don't know what happened, but my iMac just just itself down.

When I go to turn it on, the load screen appears 3/4's the way loaded, and then the whole machine turns itself off again.

I'm able to boot into utilities, but it won't let me erase and reinstall Mac OS, it says permission denied

 

[Fishrrman]

Pull the plug out of the wall and let it sit for 30 minutes.

Then plug it in and try again.

 

[g.t. rags]

after about an hour of failed tech support over the phone, they actually were able to get me in last night, had to leave the computer there overnight, and they force reinstalled the OS. Apparently, my fusion drive separated itself into two separate drives, and thats were they lost me