Log in with the default credentials (typically admin / admin ), which can be found on the bottom label of the device. : Go to Maintenance or System Settings . Select Firmware Update or Software Upgrade . Upload & Flash :
If you still require new firmware—perhaps to unlock bands, fix a boot loop, or remove carrier restrictions—follow this hierarchical, low-risk strategy:
: Some vendors offer "Exclusive" modified firmware (e.g., with Super Admin access) through platforms like Rafa Store . ⚙️ How to Update ZLT X21 Firmware