So you've turned on your new PlayStation 4 and you're greeted with a blinking blue light. Don't worry, you're not alone. A number of other users have made similar claims and while the specific cause of the error is unclear, Sony has acknowledged the issue and has created a troubleshooting guide that may help fix the problem.
The "blue light of death," as many are calling it (in reference to the Xbox 360's infamous Red Ring of Death), will result in the blue indicator light blinking, no audio/video output to the television, and the console eventually powering off. Again, there's no specific known cause, but Sony believes it could indicate TV compatibility issues, or issues with the PS4 power supply, hard drive, or other hardware; pretty broad if you ask me.
If you are experiencing this problem, Sony recommends turning off your PlayStation 4 completely by holding down the power button for at least seven sections (until the system beeps twice). Once turned off, disconnect the PS4 AC power cord from the electrical outlet and check the system's parts for any "conspicuous damage or anomalies." This includes checking the hard drive, the HDMI port, and any other input/outputs.
And if all else fails, contact PS4 customer support. Sony is continuing to investigate the issue, but they've claimed that the number of affected PS4 systems represents "less than .4% of shipped units to date," which is apparently within the company's expectations for a new product launch.