Is my tower dead or just resting ?

I've just acquired an RCX brick on behalf of my grandchildren (That's my story anyway). It had no disc with it, just a serial tower which I have provided with a new battery and plugged into the serial port. I downloaded the sdk from lego which I understand contains the firmware to get me going. I execute the program ATLclient it tells me there is no brick. Is the tower dead ? Am I doing the right thing - perhaps its an age thing (Faraday was still in short trousers when I last studied seriously). Any help would be greatly appreciated. Thanks folks !