If the green light is ON with the SD card in, then it means the SD card is detected. Check this thread, Nathan had similar symptoms. The problem was the USB drive.
As Oliver mentioned, all connections, especially HDMI, should be in before powering up the PI. HDMI 0 is the one closest to the power in USB3 connector.
In any case, try using Sandisk or Samsung EVO micro SD cards. I was using a different but UHS 3 class card on my Pi Zero W. It would have issues booting, but the files are readable using an external card reader. Finally switched to a Samsung Evo UHS 1 class. The issue went away.
