@memento.
K770...GDFS_BACKUP.bin is a GDFS backup and NOT a MAIN firmware. Download a MAIN firmware for your phone. If you don't know what to download, then post an identify log, and we will tell you...
@alternativ
Your phone is brown(EROM color), and SETool2 Lite doesn't support brown phones. Use jdflasher to flash/apply patches to phone.