Download ZTE Star 1 S20002 official firmware from the link here, and follow the provided flashing instructions to learn how to flash the stock rom.
If you notice that any of the links provided below is broken or doesn’t work, please post in comments section so we fix and update it ASAP.
File Name: ZTE S2002SD_71350B2046ZTE S2002V1.0.0B12.zip
Size: 655 MB
Android version: 4.4.2
Firmware – Download
How to flash
After downloading the above update firmware, follow the instructions here to flash.