Total Electrical failure

Hi everybody. I am going nuts here trying to solve the riddle my 2002 Octavia has thrown up. I had a problem with battery drain last week. I had to call the AA. Was told it was the charge cable that runs between the alternator and battery and the fuse box on top of the battery. The cable was over heating. I changed the harness and the fuse box. The car still started and ran until I disconnected the battery to do the changes. I left the battery disconnected over night and installed the new parts. When everything was hooked up again there is absolutely no electrical power in the car. I tried jump leads and still no power. Totally dead. Not even dash board info. I thought it might be the immobiliser but the light isn't even showing for that. Any guidance will be gratefully received.