@Sancho this is really cool, and helped to turn that device from paperweight to usable linux OS.
Everything seems "ok", though wifi is jittery at best.
I also tried building my own image from the github repo, but after completing the build and repack steps, it fails to send to the device.
$ sudo ~/Linux_Upgrade_Tool/upgrade_tool uf output/factory/apftool-rs-patched/Armbian-unofficial_26.08.0-trunk_Linknlink-isg-box-se_bookworm_vendor_6.1.115-factorytool.img
Loading firmware...
Support Type:3528 FW Ver:c.0.00 FW Time:2026-07-16 02:46:46
Loader ver:1.04 Loader Time:2023-12-13 16:28:48
Start to upgrade firmware...
Test Device Start
Test Device Success
Check Chip Start
Check Chip Success
Get FlashInfo Start
Get FlashInfo Success
Prepare IDB Start
Prepare IDB Success
Download IDB Start
Download IDB Success
Download Firmware Start
Download Firmware Fail
I'd love to experiment more with it, but no idea how to get past this part.