Solution to rescue a Macbook pro 15 2016
I had this problem as well when installing High Sierra (on day one of public release o the OS). After experiencing issues with Recovery OS as well, I took it into the Genius Bar where they were happy to help. I believe they ended up installing the OS from a recovery drive. As it was the brand new OS they had to take it overnight and contact Cupertino engineering I was told, although I would expect it to be a smooth support process by now. Best of luck getting it working quickly.