well i just got a n/a rx-7 from a friend who may have overheated the car. well any way he said it would run but not for long so i try to fire it up and see whats up. at first it would turn but would not start sounded like it did have enough power to turn it over so i tried to jump start the car (the car was sitting for a while) it didnt work after that i tried to start the car again and now it doesnt turn over it just makes this clicking sound and i noticed that the voltage guage is going all the way to 0. any ideas?

get a 19mm socket and put it on the front pulley bolt and attempt to turn the engine over by hand. More than likely the engine will turn over by hand, but still be in a bad condition, from what it sounds like is the individual that owned it before has over cranked the starter (held it cranking for over 2 minutes) and burned the windings inside. You are probably looking for a new starter. If the engine does not turn over by hand, then the starter is not the problem