That is exactly what happenned. The worst thing was my car was in the garage and becasue the auto brake was on, I could not back up to boost the car up in the driveway. My neighboor was cleaver and nice enough to remove his battery from his car and hook that up in the garage just to disable to brake. I tried to boost the car with his battery in the garage, it did not work. Then we pushed the car back into the driveway, he put the battery back into his car and gave me boost. So, I will definetely get an old school 3.5amp wall charger to prevent this happening. I also diabled auto brake permanently.
What do you mean by an "old school 3.5amp wall charger" ? To me, "old school" chargers are not wall chargers, they are the old square metal box style chargers that usually do something like 2/5/10 Amps charging or whatever.
Smart chargers are designed to protect people from exploding batteries that are being charged with dead cells. So when voltage drops below a certain threshold, the charger refuses to deliver. Even older chargers won't recognize a battery if voltage drops way down, like to 2V.
The best way to attempt a charge on such a dead battery is to hook it up to another 12V battery, in parallel, until the voltage rises enough for a charger to kick on. And a small maintainer charger (like the little Nocos) is not designed to charge a discharged car battery, but rather to top them off and maintain. For deep discharge states, you need a bulk charge from a big charger first.
Some have been able to initiate a charge with an older charger, then hook up the smart charger once it sees the battery.
What your neighbor did there was give you a sufficient parallel hook-up charge from his battery (and alternator) so that the voltage on your battery rose enough to allow the small charger to operate.
A 3.5 Amp charger is too small to charge a drained battery, no matter what they may claim. Go for a smart charger that can go up to at least 10A, for typical car batteries. The small ones that produce less than 3.5A are to be used as maintainers, basically.
Your KL battery is an AGM battery, so it will likely survive this event with only minor internal damage. Try not to let this happen again, as you are already aware, because even deep cycle / AGM batteries suffer from deep discharge state..