Comment 5 for bug 1481536

I also ran into this problem. I was able to fix it by looking at my dmesg and realizing that the proprietary ati drivers don't work with the 4.X kernel. I had the ones from ATI installed so when it'd try and boot up it'd get past the encryption but then the driver would crash.

I solved this by uninstalling my ati drivers and reinstall/reconfiguring my xorg-server.