Something one occasionally has to do on a Mac is reset the PRAM (hold down Cmd-Alt-P-R on initial startup).
However, doing this on a system with Full Disk Encryption installed may cause the Mac to appear not to boot (or to boot into the recovery image).
If this happens to you, hold down the Alt key on power up.
This will bring up a list of volumes to boot from.
For me, I had to choose the second volume listed (first one just booted into the recovery image).