For some reason the TV I was attaching the NanoPi-M4 was doing a weird overscan and dismissing the video signal entirely. Eventually after changing to a PC monitor, it started working normally.
Hello, I bought a 4GB NanoPi-M4 this November and after setting it up. Heatsink, antennas, HDMI cable to TV and microSD card flashed with either: rk3399-sd-lubuntu-desktop-xenial-4.4-armhf-20181112.img rk3399-sd-friendlydesktop-bionic-4.4-arm64-20181112.img Armbian_5.59_Nanopim4_Ubuntu_bionic_defaul...