Hi @jock,
I'm having some issues with my Rockchip 3229 TV box. It has 3GB of DDR3 ram, 4GB of NAND memory.
All images I tested including Multitool, LibreElec, Armbian crash after a few seconds. It freezes between 30 and 60 seconds. Sometimes after the system finishes booting, sometimes at boot (if the boot process takes longer, like on first boot).
It doesn't matter if I'm using an image that uses a minimal interface or with a graphical environment, it turns on the led flashes and after locking the led it stops and remains on, and usually generates some noise in the debug port.
I'll leave the boot debug logs, it's not a power source problem because I tested it with 3 others, and I also tested it on another tv box of the same model, and it had the same behavior.
Link to board photos: Google Photos
Link to the vídeo: Youtube