2003 Renault Laguna Carminat Sat NAv

hi,

i have purchased a 2003 renault laguna initiale with the carminat sat nav system. stupidly i tried to install a version of the mapping software hich was an earlier version than the one installed at the time. Now the screen is permanently blank. I have a new version of software but obviously cannot see the screen to load it.

Any ideas.

Many Thanks