Raspberry pi 2 blank TV and two lights

Ok, I got it working. I formatted the card and downloaded noobs again. Turns out I had a very old version of raspbian on that card that the pi 2 didn't seem to like. I can't believe how fast the 2 is! It starts up in about 5 seconds and loads applications almost instantly. This new version of raspbian is also a lot nicer. It feels more like a current operating system than the old one, which was a bit clunky.
The only issue I'm having now is that the rainbow square keeps coming up in the corner of the screen which I believe means there isn't enough power. I checked the rating of my power pack and it says output = 2A which should easily power the pi 2 which requires 1.8A. Think it must be a problem with my USB lead so I'll try a different one, maybe one that's slightly shorter. Shame, I like my bright green usb it goes with the blue hdmi ;)