I have the same TVbox, but i have some problem with booting armbian. I burn SD card with armbian image then dd of trust.img and uboot.img but uboot stopped at DRAM point
U-Boot 2019.10-armbian (Nov 29 2019 - 09:50:19 +0300)
Model: Rockchip RK3328 EVB
DRAM:
Tell me please how you boot armbian more details