Macbook pro wont boot, Kernel cache read error 0x6
There's probably some sort of corruption in the kernel or Kernel cache. 

Best bet would be to backup your data first, just in case, then restart and boot to your recovery volume by holding Command and R before you see the Apple logo. 

Eventually you'll be at a window with a few options including reinstalling Mac OS. If you're using wifi then connect to it in the top right corner of the screen. Choose the Reinstall option and follow the prompts, eventually selecting your boot drive as the Reinstall volume. 

It might take up to a few hours but you'll have a fresh operating system while preserving your data and should get rid of the kernel issue.