Honda CRV 04 Sat Nav, Radio, CD Unit?

Hi, i had same DVD error so sat nav was down but radio worked OK. i have carefully followed craigs instructions but when putting the unit back into the car and starting the ignition i now have a completely dead unit with no radio, CD or sat nav. Checked relevant fuse and its OK. Only strange thing was that the 'back up' fuse had blown (coincidence?) which stopped the central locking from working but when this fuse was replaced C/L was OK. However, the whole unit - ie - radio, CD & Sat Nav still dead though! Any ideas!