Alright,
Yesterday I replaced the o-ring and the other coolant elbow with an aluminum one. Pretty sure that fixed the leak, I'll drive it for a few days and we'll see.

Went to auto start my car after just for the hell of it and it worked. Weird right? I don't understand how that was the auto start problem too. Maybe disconnecting the battery did it? Even though I've done that previously to try and solve the problem.