Mine died on me out of nowhere. Barely used it. Said no 'input signal', the light on the bottom went from Blue to green then kept flashing red.
Buying this is sadly a crap shoot, which sucks because the display is great (IMO).
Preventative advice I've seen.
1. Keep it plugged in (I'd unplug mine after use for up to 3 weeks, to save on electric)
2. Only use 1 HDMI port (I was using 1 for PS3 & 1 for PC)
3. In settings, make sure Backlight isn't above 5
4. In settings, make sure to keep HDMI Control: Off
People have also mentioned the fan craps out, if you fix that you'll fix this issue.
Some people also mentioned the system (or the PS3) for some reason resets the HDMI input, so it won't show anything, but it's not 'dead'. This happened to me when I got my fixed monitor back.
Hold the PS3 Power button down until you hear 2 beeps. PS3 powers down.
Once again, Hold the PS3 Power button down until you hear 2 beeps.
When the PS3 comes back on, also make sure the TV is on, then you should see the PS3 asking if you want to use HDMI. Click yes.
Either way make sure you keep your receipt!
Sony replaced mine, sent me a box and I sent just the TV back to them.
Been working okay, but now there's a green hue on the right side....yay, time to call Sony again.