I have 2 Raspberry Pi's. the second boots up fine, but the first seems faulty.
It has never booted. I tried it initially with a long HDMI lead to my flat screen Samsung television. Nothing.
Then I tried it with the yellow lead to a small television and the screen just appears dark, no boot. There seem to be 3 lights on the board although it is difficult to tell.
I tried the same 5v power supply, SD card and lead with the same small television and the second Raspberry Pi and it works fine, which seems to prove that all these items are ok. I even just tried swopping just the SD cards. Both cards work fine with the second Pi and were supplied with Debian pre installed. Both Pi's are 512 standard.
The second Pi also works fine with a keyboard and mouse fitted.
I fiddled about and then noticed that by now, I seemed to have damaged the SD card slot of the first Pi. I have subsequently fixed it with the glued credit card and shim trick shown on several sites. This seems fine, but still no boot or screen from the first Pi.
Any ideas? Shame to waste the first Pi which I bought for my daughter.