Installing Operating System Images
One of the most common issues that see here at PiShop is people thinking that their Pi board is DOA when an operating system image is created incorrectly. If the OS files are simply copied onto the microSD card rather than using an imaging program such as Etcher or Win32diskimager, the operating system WILL NOT BOOT, and the Pi board will appear non-functional.
Please see this simple, clear guide on the Raspberry Pi Foundation support site for how to correctly image an operating system onto the microSD card!
Happy imaging :)