I have tried using two different brand new SD cards and my Pi refuses to boot. There is no green light at all, not even a flicker. I have used the official SD card formatter and installed N00bs and also used etcher to write raspbian directly to the card. I am using an official power supply and all I get is the rainbow screen. I have tried every other troubleshooting forum and guide but I can't find anything helpful. I have heard that every Pi is able to boot when it leaves the factory so it is unlikely that the board is a dud. The pi foundation website is useless as it just links to more guides on how to install N00bs, which I have done and redone about 10 times now. I can clearly see that boot\kernel.img is present on the boot partition of the card but the pi refuses to read anything or show any signs of screen activity.