Black screen with a crossed out circle when powering on

after updating to OS 10.10.4 I could not get my Mac mini to awake from sleep mode. I tried to restore from time machine back up from just before the update. It stated that the restore was successful but now I have the problem of a black screen with a white circle crossed out in the center. My Mac mini is a Late 2012 i7 with a fusion drive. I've had no issues before this.