Well, as it was a direct short it took about 3sec. Than the batteries start to blow gas into the air. After 30sec. they start to blown up under the the battery tray. Flames I have seen only after the battery tray was totally destroyed. I first threw the two plankets over the board. It held back the flying hot melted rubber and other parts when the cells exploded. Our 30sqm room was totally filled with smoke after 1min and I needed to leave the room to breath and come back. After this I used the fire extinguishers. Unfortunately I bought just the small one for cars. Was enough for 30sec. to cover the batteries, but not enough to shut down the fire. The cells start to fire from inside again and again. I was waiting for 1-2min than used the salt water, which finally stopped everything from burning. I wouldn’t use the water in first place as it would just run away fast. If the cells already close to burn out it helps very good. Can’t say if you really need salt water or if in my case just water would be enough. All in all it took me five to seven minutes till all fire was shut down.
I wouldn’t recommend to hold your board in the hands after cells start to burn. They sometimes explode and hot melted rubber fly around or flames spiking. I‘m very happy that I had the blanks which covered the most shit. One wall was not totally lucky and got a nice mosaic of hot rubber-plastic. Luckily it didn’t hit me.
What gauge of wire where you running for your charge port?
I used 12AWG
Seems as you suggest to use a really small gauge wire to act like a fuse. Good Tip!
Just select the wire to the charging current 
Tho I don’t have any hard evidence to back this up I think it’s much safer to use thin cables that are rated lower and they’d hopefully burn out in this kind of situation.
Something to keep in mind for future builds
Just don’t use the same plug…or just turn them arround. Charge male discharge female. It would already saved my board and a lot of troubles
Personally I just run a single xt90 for charging with a wireless power switch. Still worried that someone else might mistake it for a loopkey port someday.
Use xt60 for charge port. As far as I know there are no xt60 anti spark plugs
thin wires + fuse + bms + different ports/plugs. No reason to only use one Method. Better be Safe than sorry.
Thanks for sharing. Did you manage to remove the loop key at any point?
My thoughts exactly. A high amp non bypassed BMS would have shut the power down before any damage could occur.
I shorted my charging port once and my bms shut it down instantly so only the charge port was damaged
It was a compact loop key. No way to get it out in the 3sec. before it start to burn
Thanks. Was wondering if it continued to burn after short-circuit was removed. As in, if it happens to me do I dive in and pull that sucker out at all cost. 
Must have been nuts.
Glad the damage was limited to the board. With short lengths of 12awg you were probably pushing hundreds of amps immediately. A thinner wire would have fried well before that 
Probably. Now I would make a lot of things different.
If you have a loop key with a „loop“ I think it could have been possible. In case the plug don’t weld together because of high current
THAT was your first build?? I’m sorry for your loss, great looking board. Like @Eboosted , I see an even more impressive build in your future. As @deucesdown said, thanks for sharing this
I would probably put in a claim to my home owners insurance, at least that would take a little of the sting out of your loss.
Unfortunatelly here in Russia nobody will mind about it.