Find your specific firmware file and drag it directly onto the Brother Maintenance USB Printer icon within the FILEDG32 window.
The printer's lights will typically flash to indicate data is being received. Do not unplug the machine during this phase, as it can permanently damage the main PCB. Risks and Safety Warning
The printer must be recognized as a "Brother Maintenance USB Printer" in the Device Manager. This requires a separate "BHL2-Maintenance" or "Maintenance Driver" package often found in technical service bundles.