macbook pro does not boot after upgrade

After allowing an update, the computer no longer boots all the way. The screen looks like the computer is showing the wrong memory as if the graphics was memory mapped. See image. Progress bar only gets 1/2 way then freezes. Plugging in an external drive and starting while holding the Option key gives the same messed up graphics. I can pick the external hard drive, but the progress bar doesn't make it all the way. Looking forward to any help on this. Thanks.