The X won't start. What could it be.

[xRide]

My 05 4.8is will not start.

I drove it to the mall and had it running while I went to a store and back out. Didn't take me 5 minutes. As soon as i returned, my cousin who was sitting in the car said it shut off for no reason. I tried to start it and it started back up after a few tries. Drove it home and as soon as I pulled into the driveway it shuts off again.

I went to check the battery terminals and found that the positive terminal was loose all this time. Didn't have a tight connection. I tightened it and started, but then died again.

Now its completely dead. It's not cranking at all. Sometime you get a click, other times its nothing. Just lights. At one point not even lights came up.

I purchased a new Exide battery and that didnt help. It didnt even start with the new battery. But I am not sure about the new battery because the fluid inside was leaking out and the cap for 2 of the fill holes on the batter was loose and looked as if someone opened it.

I tried to jump start it and still nothing

The alternator was replaced August of 2013; last year.

What could possibly cause it to not even cranking, but all lights work and it seemed the battery is good. The battery is a BMW battery. I don't know if it is original.

I also want to note that the 4x4 light came up, SUS INACT, Engine failsafe and Transmission fail safe came up.

These were the same lights when the Alternator went last year, but it was starting.