for any available offline download packages, though these are often region-specific. ZTE Official Website Community & Third-Party Resources
The ZTE MU5001 uses a . If you flash a firmware file signed with the wrong key (e.g., a Chinese MU5001-6 file onto a European MU5001-2), the bootloader will reject it. Unfortunately, the device does not "reject" it gracefully—it erases the current bootloader, tries to install the new one, fails, and leaves a paperweight. zte mu5001 firmware link