It's already there :)

Look in the Files section; in the MATRIX DOC's folder you'll find a RAR archive containing the original firmware V1.11, and the presets ROM. To save you the hassle of unRARing the archive, I'll attach the file to this message. It's just as I took it from the archive, I did not check its validity.

If that does not work, I've got to take my Matrix apart again and copy the EPROM.