Ok, moving the discussion here from this post:
So I updated the firmware following the instructions in that post, but then I lost hdmi output, meaning that when I connect the display and turn on the board I get a black screen, I do not even get the u-boot output, absolutely nothing.
I got a usb a to a cable and tried flashing it with pyamlboot following these instructions.
And again I got no hdmi output at all. So I looked up the code and noticed that all the firmware is coming from loverpi.com.
Since the board was shipped with 2019.04 firmware, I tried all the 2019 versions starting from r5, again no hdmi, until I got to u-boot-2019-04-r1.bin. This is the only u-boot version that has hdmi working on my board.
Since all boards are supposed to ship with the latest firmware, is it possible that I just got a lemon?