First, the only way for me to enter the Service Menu again, was to reset the EEPROM (see Wiki). The Wiki states that you have to remove the Bridge after the Message appears and than start again but this results in the same boot loop. I had to leave the bridge, shutdown the TV, start in Service Menu and than remove it and change settings.
Next problem, after setting region back to EU and do another factory reset, boot loop still persist.
I repeated the Steps some times and tried to different things with no luck. Then I saw that the TV always starts in HDMI1/DVI but without showing anything. So I had to reset the EEPROM again and directly after the message did a scan (without EEPROM bridge). After it found some TV stations I stopped the scan, switched to the first not encrypted one and restarted the TV in Service Menu mode. This time it worked without bridge and after another restart all were functioning as before :)
So the main problem were missing TV station because of the factory reset. I wanted to share this in hope its useful for someone else.