Hi,
that's the board that I successfully booted from SD card using Legacy LibreELEC-RK322x.arm-9.2-devel-20200427220345-b7186bc-rk3229-hk1mini.img.gz image (first image I tried).
Then I tried with Mainline LibreELEC-RK322x.arm-9.80-devel-20200228171244-cd590c7-rk3229-box.img.gz but it didn't boot (blank screen on HDMI).
Board is definitely RK3229, has 8GB NAND flash and 2GB DDR3.
Any clue where to start investigations ?
many thanks