If you've been letting the battery "die" to the point it won't start the car, it's likely junk even in the event it's not the root cause. (though it usually is).
Unlike a deep cycle, starting batteries are not tolerant to being that deeply discharged. Each time it happens, the battery loses capacity, and it loses what charge it does have much quicker, even without an abnormal parasitic current draw. (which should be no more than 20mA or so when the car is in "sleep mode").
Letting it go dead once or twice you'll probably get by with and successfully recharge it to maybe 80% capacity, and on a daily driven car, it may seem fine and last a while like that, but realize the damage is already done and that battery is never fully recharging, and never will again.
If the battery has gone dead more times than that in it's lifetime, the battery is junk, period.
Drop a new battery in it, and I'll bet you can let the car sit for the next month and it'll start up just fine.
