MBP boot stuck at 100% loading screen
The problem is unsupported .kext files and you need to remove them to get OS X to boot.  Just moving them to a different directy will have the same effect but will allow you to copy them back.  This article had the solution for me: OS X El Capitan 10.11.x Hanging on Boot

mount -rw /
cd /Volumes/Macintosh\ HD/Library/Extensions/
mkdir Unsupported
mv *.kext Unsupported
reboot


After solving that issue, I ended up with a black screen where I could only see my cursor.  If that happens to you, try the solution found here:  Black Screen But Can See My Cursor