If the tool fails step 4, your BIOS chip has valid code inside, but the computer thinks the file size is 0 bytes. Result: A black screen on boot.
Let’s walk through a classic mod:
The tool is not officially open-source, but various versions (including patched or reverse-engineered builds) have been uploaded to GitHub by third-party users for archival, educational, or utility purposes. It is widely used in firmware modding communities (e.g., BIOS-mods, Win-Raid) for tasks like adding NVMe support, inserting SLIC tables, or updating CPU microcode. mmtool github