I solved it, in the end I had to add a few lines in /boot/config.txt to change HDMI group to DMT and try different HDMI modes until getting one showing the screen properly.
I have a 5 V 0.2 Amps PI-FAN that's also that loud when connected to its 5V rating, but it's close to silent if I use the 3.3 V pin (so I have it like so). You should give it a try, with passive cooling underneath it's more than enough.
I've installed Ubuntu Server 19.10.1 for Pi without a hitch. It works as expected BUT I can't see the left side of the screen, which makes editing txt files close to impossible. I'm connecting my RBPi4B to an OLED 4K LG TV. Any ideas?