I have two laptops, one (VAIO Pro 13) updated to preview 17074.1002 just fine. The other one (Toshiba Portege z30) failed to boot after installing the update.
The update was downloaded and installed, I restarted the laptop. It booted up to a green screen saying it was updating, and after 100% it restarted again, but this time it failed to start. The screen was stuck at the Toshiba logo and a spinning circle of dots. I went to do something else more than 30 minutes and the laptop still stuck at the same screen. I had to press and hold the power button to restart it. It booted up and stuck at the same screen.
Another one or two attempts of restart then it reverted back to the previous working update. Tried updating again for a few times and still got the same problem.