Kotaku and IGN received consoles unable to output through HDMI, in the latter's case after updating the firmware to 1.50 and downloading the Netflix app.
While it's unclear what exactly caused IGN's PS4 to stop working, Sony was able to quickly identify and fix the issue with Kotaku's unit. As Sony reps told the site, an "obstructing piece of metal" in the PS4 had knocked some of the connecting "teeth" out of inserted HDMI cables. Neither Kotaku nor Sony was able to explain how the issue arose, although the site didn't discount human error from its end.
Meanwhile, a Reddit user who received a PS4 early through a promotion also experienced issues; his PS4 turned on, producing the blue pulsating light on the console, but wouldn't send a signal to TV. The issue with his unit remains unresolved, but Sony will provide him with a replacement unit.
Responding to these reports and ones that surfaced elsewhere including on NeoGAF, Sony Worldwide Studios boss Shuhei Yoshida tweeted, "Be assured we are investigating reported PS4 issues. The number is very small compared to shipped, we believe they are isolated incidents."