A few days ago, when I turned (a rather old, 8y maybe) notebook I have the fans started to spin in full power mode and I have no display output when I connect the notebook to a screen.
When it unplug the power cord, so that it runs from its battery, the fans don’t spin up this much, but it still doesn’t boot into the OS.
Difficult to say, the internal but removed screen is 80% broken and I still need to retest a couple of time to be 100% confident. The external screen doesn’t change anything, but even with the notebook working correctly it only gets activated when the notebook starts the display manager.
I’d try reseating the RAM within the laptop. I’ve seen it many times where an old computer will randomly stop working one day, and reseating the RAM fixes it.