Black Screen on MacBook Pro 2018

Run Apple Diagnostics to check for hardware failure.

How to use Apple Diagnostics on your Mac - Apple Support

Note that Apple Diagnostics is not the most sensitive test. If it reports there is a problem you can be pretty sure there is one but just because it reports no problems doesn't mean that one doesn't exist. Apple has much more extensive hardware tests they can run.

I have the same exact issue, with a new i7 15" MBP, and no external monitor to project to! Spent some time on chat support this morning with not much help. I'm curious [OP] as to whether resetting SMC actually would execute properly? Not being able to see anything, the behavior of some of these troubleshooting routines is not what is written. For instance, powering off the "hard way" by just holding the power key forever does SEEM to shut the system down, but then if I do the three-key, plus 4, SMC reset, the system seems to turn "On" about 7 seconds or so after adding the power button. In other words, the system appears OFF, I hold the left Control&Option keys while holding the right Shift key for 7 seconds, then add to the hold the power button for 7 seconds but while I'm in that hold position the system seems to turn ON - keyboard lights up, the bar lights up.

Similarly, when the system APPEARS to be sleeping, i.e. powered-up, keyboard lit, then I shut the lid, leave it alone for a good 30 minutes or more, then open it, all I see is the ESC key lit. Nothing else is responding. No choices but to hold the power button long again.

We're just shy of an hour from nearest service repair outfit. Or mail....

not the best reliability I have seen

Bring it in for a free diagnostic. If it is relatively new, under a year you're covered under warranty for repairs. If you have AppleCare Plus better yet.

Yes, I'm sure it's difficult to carry around with a TV attached. I wish I could give you a better solution.