Check the main fuse in the fuse box front left inside the bonnet should say (main fuse) its a 60 amp . and check if the negative between the body, battery,and engine (connect to gearbox ) if they clean and connected.
Hope it help.
Reason about fuse was mine had a similair problem currently it runs with a thick wire link in the fuse's place bit dodgey but it works .
battlecat
January 2007