I saved the URL of this thread in November 2016, when I had the same exact issue. At that point, there were no solutions posted. I put my 2014 MBP away in the attic, bought a used late 2008 unibody, and used that for the past three years.
The 2008 has served me exceptionally well. Absolutely no complaints. I'm using it right now.
In early November 2016, my 2014 MBP would not wake up after I put it to sleep. I could tell that it was running, but the screen was black. I read about the issue and found that it might be possible to use the external HDMI monitor. That worked, in Safe Mode only. I reinstalled the OS, ran hardware tests, and got the response "There may be an issue with the display." VFD002
This thread deals with the same issue, and offers some insights and troubleshooting steps, as well as the opinion that the issue is caused by an unseated or intermittent cable: https://discussions.apple.com/thread/7077614
I recently got the itch to try to resurrect the broken 2014 MBP, so I revisited this link and saw the posts by Michael_mhr and ardaviraf sharing the solution of applying pressure to the display.
I attached the power supply to the 2014 MBP. It immediately chimed and looked like it was again booting to a black screen. I quickly squeezed both lower corners of the display and for the first time in over three years, I saw the normal login screen. It has been behaving fine since then, with no need to manipulate the display. I have put it to sleep, woken it, shut it down and restarted it - all with success.
Back in 2016, the only way I could get it to boot was through an external HDMI monitor, in safe mode. Google Chrome would not even start up.
Until I saw the good news here, I had given up on fixing it, and I am really
glad about that. The only expert advice I had found was that the integrated Iris video chip had dislodged from its bed of microscopic solder balls, and that it could perhaps be fixed by baking or replacing the motherboard. The other thread mentions a quote of $1,100 for Apple to fix the issue.
I'm not sure if the squeezing trick resurrected my MBP, or if perhaps all volatile settings had been flushed. The battery had drained to 0% and the clock had reset to Jan 01 2015, so that may have been a factor. In any case, thanks to all who have taken time to post their frustrations and triumphs regarding this issue. I am in your debt.