2 door Deville -Can't start

Any battery that has not been exersized in 6 months will drain down to a point that is will not start the car. Remember, the car needs electricity to keep your engine settings and radio clock and other stuff powered up even when the car is just sitting. If the battery was new when you installed it you can probably jump it and then run the car without shutting it down for 15-30 minutes of driving. Then put a charger on the car if you are just going to let it sit.

Taver, Thank you for your prompt response. I bought a battery charger and charged the battery. Drove the car for half an hour and left it in the garage. After two weeks I tried to start it again, it didn't work. Connected the battery to the charger, it was 40 %. Got it charged but this time couldn't start a car. When I turned the key the lights turned on for a moment and turned of. Did the starter, that gives it initial boost a 1000 amps to turn the engine, died? or there is something else. The Battery spec says it can provide 800 amps in cold weather.