Electrical system dead

I am repairing a 1987 Plymouth Gran Fury, and the electrical system seems dead. I know the battery is shot since I tested it with a battery charger. I am using the battery charger both on the 10 amp recharge and the startup settings. I have replaced the distributor cap, the rotor, the 8 spark plugs, the air filter pcv valve and the breather element. The horn, the lights- interior and external, the radio etc do absolutely nothing with the battery charger. The car does not even start to crank. Does anybody have any idea what may be wrong? Does anybody have any suggestions? Thanks