First off, this is the 4th generation of Pi that I've owned, so I'm not a noob. I just received my Pi 4 and recommended PSU from PiShop US. I've created both a Raspbian and Gentoo SD card with new 32gb class 10 cards. At first I tried using a 12ft HDMI to HDMI Micro cable, but each time I tried to boot, I could see the green led flashing normally but had nothing on the 40" monitor except the message saying "no source". I tried several times with both the Raspbian and Gentoo cards. At one time, using the Gentoo the screen worked, but I soon as I rebooted, it failed again. I also have a 32" monitor and that didn't work either. So, thinking it must be the cable, I hunted through my spare parts box and found an HDMI to Micro pig tail and used it with a 4ft cable and thought I had the problem solved. It booted both the Raspbian and Gentoo cards. But after going through the Raspbian setup and update process, it again failed when I rebooted. So, thinking the update must I corrupted the Raspbian, I tried the Gentoo and now it doesn't work either. Burned Raspbian again and it doesn't work either. In all cases the green led flickers normally.