If I'm understanding correctly (very new to this..) tty is the terminal, so if you can't access that it's not a problem with drivers, I don't think. It sounds like you may know more than me, but the only thing I didn't see you mention was if you were using eufi boot or legacy boot, which I saw caused issues with other people (I forget if it needed eufi turned off, or on, mine worked with EUFI but mine will start EUFI then attempt legacy boot so idk if that provided a workaround for me..)
You said sometimes you get the blinking cursor (I assume you mean underscore?) So if it's varying from that and an all black screen,
I would think something is being read sometimes and not read other times, which is why that variance occurs.. what that could be, I have no idea. Hopefully someone smarter/more knowledgeable than me can help, but it may be a good idea to record it booting up, so you can see what processes are occuring and if it says what it's attempting to do before the failure?
