Re: re. Anyone who tells you Linux is hard to use wasn't paying attention
"As other have mentioned though the Pi running Linux is meant as a device for tinkering around with so you kind of expect there to be more teething troubles than connecting a consumer device such as your average desktop PC."
Don't give me that. I'm mostly on the Linux side of this argument, but not when people react like that. If we're to succeed in arguing that Linux is suitable for general use, we can't react every time a bug is found by inventing a reason why it's not a problem there's a bug there. And by the way, I'm not yet convinced this is a software problem (explanation below), but your argument applies whether this is or not, so I'll deal with it first.
The Raspberry Pi is designed for education, has OS integration directly with the hardware, and has a decade of hardware and software experience. It can get away with many problems, but it can't get away with failure to function. I'm not expecting that it will repair itself after you mess around with it, but if it can't power on and use its basic peripherals, that's a critical bug requiring a patch. In my use of the Pi, I haven't encountered many of these and fortunately, the Raspbian developers appear to take my view on it more than yours. If we can confirm that it is a software issue causing this failure, it requires an immediate fix and should not be an accepted "teething trouble".
All that said, I think this might be a hardware issue, specifically an issue with the HDMI ports on the failing Pi. This can be tested; swap the SD cards between the Pis. If the same card is failing, then it's a problem with the system on that card, and a reimage could fix it and is worth a try. If the Pi continues to fail with the card that formerly worked, then it's probably a hardware issue, though you could always try replacing the embedded firmware if it's a Pi 4. The hardware issue could be in the HDMI port or controller, which would exhibit the same behavior no matter what cable or display was used.