its a 87 cadillac, wont start,went totally dead,wouldnt do anything, tightened up the battery cables, cleaned off corrosion, now it will turn over but still no dash lights and its getting no fuel which the fuel pump is electical as well. Could be a computer,fuseable link? what do you think is the problem

Optional Information:
1987 Cadillac Fleetwood 4.1 Liter

Already Tried:
battery,cables,