Couldn't set it anymore to SiRF to Flash it or ANYTHING! ). But as I wanted to be 'up-to-date', I searched the Web for some more recent Firmware, stumbled upon some, flashed - and killed the Mouse ~.~''. I did solder my own Data and Poweradaptor, which worked great.
Its an really cool looking Mouse (Serial/Usb depending on the properitary Connector you attach), powered by an Y-Cable with 5 Pins, powered by an quite old SiRF 2 Chipset. Hi there, I was working on an Serial GPS Mouse, Type Royaltek RGM 2000, also called 'Blue Mouse', which became famous for beeing deployed with an Medion GPS Kit Years ago.