I stop editing my first post and make a new one.
I looked up the log files. I found this:
Warning: C:\Axon10_EDL_TOOL_v3.2.5\backup\all\last_parti1.bin - not found !!!
Warning: C:\Axon10_EDL_TOOL_v3.2.5\backup\all\last_parti2.bin - not found !!!
Warning: C:\Axon10_EDL_TOOL_v3.2.5\backup\all\last_parti3 - not found !!!
Warning: C:\Axon10_EDL_TOOL_v3.2.5\backup\all\last_parti4.bin - not found !!!
Warning: C:\Axon10_EDL_TOOL_v3.2.5\backup\all\last_parti5 - not found !!!
Indeed the files are missing. But why? Can anybody tell? How could I make something wrong with a backup?
Am I right that I first have to lock the bootloader to get away of bootloop? And maybe the backup will work after that? If yes, how can I do it?
Edit: Managed to flash EDL Full 1.6. Got Android 9 running right now, but still with bootloader unlocked. Which means I can not flash any stock android higher than 9, correct? So, should I lock the bootloader or should I root and flash LOS? Somebody reading this at all? :-D