Upgrade from 18.04 to 20.04 froze.

I was prompted to upgrade to Focal Fossa. After a while progress froze, went to bed to give it more item to update. 7 hours later still frozen on same screen. Hit power button (Did not know [Ctrl][Alt]+[SysRq] REISUB existed at the time).
Boots up to the Ubuntu loading screen. Then it loads up a black console for about 1 second, power cuts off to the monitor for a second. This repeats. I will test newer Ubuntu upgrades from a USB stick from now on. Currently using 18.04.3 boot stick on the only USB I have available.
What steps should I take to repair my system?

Thanks in advance.

Many things can go wrong for a failed upgrade. There's one possible cause that may be easily solvable, which is a graphics driver issue, which could lead to black screens. Can you boot in save graphics using recovery mode? If that works, it may be easy to fix. Otherwise the best approach is a fresh install.

Thanks! Turns out one of my ram cards suddenly died. Diagnosing that was not fun.