2008 SAAB 9-3 2T Aero electrical fault.

Hi,
my SAAB has developed a slow electrical discharge/short.
If I don't drive it for more that 3 days, the battery goes flat.
An auto electrician located the circuit at fault - Main Fuse №1 for Dashboard Electrical Centre.
Trouble is, he has no idea what that means or how to fix it.
By removing this fuse, the battery will hold charge for a week or more, but that's a real sweat.

Does anyone know what the error means and - even better - how to fix it please.

Thanks in advance,

Keith