Sudden Mojave death after starting update.

Hi all. Tonight my Hackintosh booted and updated because i had not been paying enough attention to it wanting to update.

It boots to a black screen with nothing on it but if press keys on the keyboard the screen flashes.

I will probably try again tomorrow with a fresh head but is there any suggestions on where to start? I guess I should have expected this as my install a couple of months back went super smoothly.

It's a vanilla install on z370 board, 8350k i3 and an rx580.

Thanks y'all.