Firmware for the B760HS3 is rarely hosted on public servers like ZTE’s global website. Because these devices are "white-labeled" for ISPs, the firmware is customized per carrier (e.g., different boot logos, hardcoded server URLs, DRM keys). A firmware meant for Provider A will likely brick a device issued by Provider B.

If you have exhausted all search options, consider these alternatives:

If the device is still functional and connected to the ISP network:

If your ZTE B760HS3 can still boot to the home screen but fails to auto-update, you can force an update via ADB.

Often caused by a failed OTA update or corrupted system partition.