You can find the download link of ZTE Quest 5 Z3351S Stock Firmware ROM (flash file) on this page. The Stock Firmware comes in a zip package that contains the original Firmware, Flash Tool, Driver, and How-to Flash manual.
You can use the ZTE firmware to Upgrade or Downgrade the Operating System (OS) of the device, Unlock or remove the device’s protection, Fix the IMEI-related issue, or Fix the bootloop problem.
File Name: ZTE_Quest_5_Z3351S_MT6739_USA_399190B3330Z3351SV1.0.0B14_Z3351SV1.0.0B33.zip
File Size: 946 MB
Flash Tool: SP Flash Tool for Windows | SP Flash Tool for Linux
How-to Flash (install): Follow Guidelines
[*] Caution: We do NOT recommend you to Flash the preloader.bin, as it may brick the device. Therefore, we recommend you to Untick the Preloader option while flashing or installing the device’s firmware.
[*] Backup: We recommend taking a backup of your data before flashing or installing the Stock Firmware (ROM), as flashing the Firmware will wipe the data from the device.
[*] Original firmware: We only Serve the original firmware, which the device manufacturer releases, and we scan each of the firmware using MalwareBytes Premium before sharing it online.