There are sporadic reports across the web that some PS4 early adopters are experiencing hardware issues. One of the problems relates to a flashing blue light that appears on the console.
If you boot up the PS4, see a blank screen and a flashing blue light then follow this fix.
1. Remove the HDD
2. Switch on the PS4
3. Turn the PS4 off
3. Insert the HDD
4.Turn the PS4 on.
Some users believe the issue is a fragmented hard drive and the above fix will re-format it so that you can boot up your PS4 and start playing.
If this fix doesn't work, contact Sony Customer Services.