There isn't a single "universal" tool for all Huawei modems. The method depends heavily on the specific model and hardware version.
If you are uncomfortable with leaked tools, consider these official or safer methods: huawei ont firmware flash tool
Abstract
The Huawei Optical Network Terminal (ONT) firmware flash tool is a specialized utility used for low-level firmware recovery, bootloader repair, and system restoration on Huawei-branded GPON/EPON ONT devices. This paper examines the tool’s architecture, operational principles, supported interfaces (serial, TFTP, and HTTP), safety mechanisms, and practical use cases in both field maintenance and laboratory reverse engineering. There isn't a single "universal" tool for all Huawei modems
WAP> display version
The firmware of a Huawei ONT is not a single file. It usually consists of: Verify firmware version: WAP> display version