1979 300sd

[robertbrown29]

three days ago,the battery on my 1979 300sd died.after receiving a warranty replacement battery and installing it,there is plenty of battery power,but nothing happens when you turn the key to start the car.glow plug relay clicks,but the starter solanoid does not.the flat 50amp fuse in the relay box gets very hot.when turning the key to start ,the dash lights do not dim.it is as if there is no drain from the starter.what should I check?thank you.