Finding the official can be tricky because Huawei removed official firmware downloads for legacy devices. Do not download random EXE files from pop-up ads. Stick to trusted sources.
On the CHM-U01, the proinfo partition (containing factory SN) sits between seccfg and nvram . If you shift offsets even by 1 byte, the eMMC’s GPT and the scatter will mismatch, leading to S_FTHND_FILE_IS_NOT_LOADED_YET or STATUS_EXT_RAM_EXCEPTION errors. Chm-u01 Firmware Scatter