If the router is "bricked" (wont boot), advanced recovery methods are required. ZTE MF920VS – обсуждение - 4PDA
The is not a magic utility but a process requiring research, caution, and the right hardware. If your goal is simply to update firmware, use the router’s web interface (Administration > Firmware Upgrade). Only venture into TFTP, U-Boot, or serial flashing if the router is already bricked or you need advanced features like OpenWrt.
Used specifically for ZTE devices powered by MediaTek (MTK) chipsets. It requires a "scatter file" to map the device's partitions. Common Use Cases [Guide] de-bricking a ZTE Blade - MoDaCo