Elysium, no idea at the moment... let's think a little...
Well no idea, except that log should be in /dtv/FWdowngrade.log precisely, and of course it's gone after reboot... Rest I forgot everything, and I never reversed any GAS6 anyway
If "downgrade to lower" had been asked, lib did its job. It basically does no more on other series.
The 1% issue seem to be really weird. Indeed, log is required, @Elysium. What you could do is:
1. Run the lib
2. Attach USB with firmware downgrade file (unzipped of-course!) with T-GAS6DEUC directory in root of USB
3. Navigate via menu and start "upgrade" trough USB
4. When you are asked to reboot, connect to tv via ftp and get /dtv/FWdowngrade.log
5. Click on reboot (or what you supposed to press on to continue downgrade)...
6. Attach log file here
I ordered the parts for ExLink cable, I will build it next week.
For better understanding, would be great if it was in English