@jock, sorry for the confusion actually there are two boards (two different TV-BOX) one (here in this post) is an rk3318-H50 as you say T98... using FD650, the other one is rk3318-T9 (only T9) using FD655. All the dtso files posted are correct: for the H50 (T98) in this post you have the versions for the old kernel and the new one. Same in the other post "HELP WANTED" for the other TV BOX. At the end the two latest dtso are valid for the latest kernel. One of the difference between FD650 and FD655 is that the first one has 4 digits but 8 segments (0-7) on the contrary FD655 drives 5 digits and 7 segments (0..6). DTSO files are configured accordingly and fully working. Hope it clarifies.

After wanting to use Debian 13 (Trixie) @Nick A suggested trying to build it myself, and this was my first experience building an Armbian image. I encountered some obstacles, but I got through them. I saw that the model was mentioned branch v20251014. I tried building it (Mate Desktop), which as build smoother than (v20250306) before. I tried booting it with this box (Transpeed 8K618-T) and and found that the wifi was not visible. I followed the troubleshooting methods in the previous thread solved it. I have installed additional IR remote and OpenVFD. Now everything is smooth and happy. The only thing left is the video acceleration, but that would be difficult because it is beyond my ability. Finally, thank you, @Nick A

Even though current is an LTS kernel it probably makes more sense to focus on vendor an edge. vendor because its rockchip bsp and close to being feature-complete. And edge for likely becoming the next LTS kernel which ultimately become current at some point. You can try to see what actually works on current at this time. You can ignore 6.15-6.17 since those patches, if still present, are for archival purposes only and will be remove at some point. In theory it could be re-used but may introduce confusion. If in doubt, copy and rename. Edit: Seems like lots of stuff has been mainlined already. So I suggest shifting your primary focus on edge.

@jock I didn't know the problem could be the watchdog, nor did I know about the existence of the open-source Trust OS. Do you think it's feasible to include the open-source Trust OS in this testing process, or does the open-source Trust OS solve all these problems? My idea wasn't to change it at runtime; my idea is to flash, reboot, test, save the result, repeatedly until all possible combinations are exhausted.

@Gian Luca Please try libMali route: + Flash Armbian 25.8.1 Noble Gnome (Vendor Kernel: 6.1.115) + Disable the Panthor overlay + Install libMali https://github.com/ginkage/libmali-rockchip/releases/download/v1.9-1-04f8711/libmali-valhall-g610-g24p0-wayland-gbm_1.9-1_arm64.deb + Install the WSI https://github.com/ginkage/vulkan-wsi-layer/releases/tag/v1.3.276-1-d48decd (for Wayland, XWayland only) mesa (Panfrost/PanVk) route: + Flash Armbian 25.8.1 Noble Gnome/XFCE (Vendor Kernel: 6.1.115) + Enable the Panthor overlay + Install the "mesa-vulkan-drivers" https://launchpad.net/~ernstp/+archive/ubuntu/mesarc (for both Wayland and X11)