Download 4.2.9 Stock Firmware for Doogee DG550 smartphone from here, here or here.
Archive name: DOOGEE_DAGGER_DG550_Android_4.2.9_20140613
Archive file size: 327 MB
Support: Mediatek MT6592
Project: ratech92_wet_rlk_jb9
Config_version: V1.1.2
ADS HERE !!!