Before attempting technical surgery, check if your "emergency files" are already synced:
Microsoft maintains a server for official FFU files. You do not need to manually download "emergency files" from third-party sites if using the official tool. lumia 650 emergency files portable
: Older models (e.g., Lumia 520, 920, 1020) rely on .hex and .mbn partition tables to initialize a recovery flash. Before attempting technical surgery