I had Windows 8.1 Pro running just fine on a bootcamp partition on my 2015 15" rMBP w/dGPU. I followed the tutorial on upgrading to Windows 10 Pro. That went fine except the screen resolution was tiny but I figured it was something I could fix later because I wanted to do a clean install. I went through the steps to create a usb flash drive installer. I deleted the bootcamp partition in Yosemite and proceeded with creating a new bootcamp partition, downloaded the Apple drivers, etc.. This is where I'm failing. I rebooted and pointed to start from the Windows 10 installer flash drive but nothing happens then the computer reboots into OS X. What should I do now?