crwdns2934241:0crwdne2934241:0 Xen

crwdns2934249:0crwdne2934249:0:

You want to try resetting the PRAM. Hold command, option p and r while booting the system. You want to wait till it restarts twice. So the third time you hear the initial chime let go and let it boot up. As long it is just the video setting and not the backlight being out this should help.

crwdns2915684:0crwdne2915684:0:

open