Allot of guessing here with out more info. Turn on your headlights if they are bright try to start the car...Observe the head lights, if they go dim your battery might need charged. If there is no change in your lights you might have a defective neutral safety switch. If they go out you have a bad connection at battery or a bad ground.
what makes you think the bat is dead it may be the starter or the post on the bat are lose or need cleaning if the bat is dead it could be the cables you are useing thay make some realy cheep ones that dont carey the amps to start a car if its bat is all the way dead
by the way i have a black 92 Corvette convertible and i wouldent give it up for any thing take care of yours