Fixed it by doing the following.
1. Download 2.5.3 boot.bat file.
2. Copied boot.bat file to root of SD card.
3. Boot to SX dongle.
4. Clicked boot to CFW. It will warn you that you don't have license.bat.
5. Generate license-request.bat file.
6. Don't continue to boot to CFW.
7. Use https://sx.xecuter.com to generate license.bat file using the generated license-request.bat in Step #5.
8. Download 2.6 boot.bat file.
9. Overwrite the boot.bat file in your SD card with the new one.
10. Boot SX OS.
wollte ich fragen hat einer 2.5.3 boot.bat
finde netz nichts