Thats good new, I was afraid it would, so thats why I trow it away right away. The battery still smells burned, I have had it on my table now for the last hour or so, while I have taken the pictures, so maybe two hours. And it smells electrical burn from it. But it’s not hot or something, and the Voltage is still 4.20 (tested just now). Is any danger to have it on my table, or should I put it back into my fireplace there it’s safe?
As long as it is cool, there is no danger.
should we all express doubt about that cell being still good and is internally shorted/is bad and should be discarded (with proper methods, of course)?
I did something like this once and all the cell had reduced performance. I did recycle them.
And I will recycle this battery also. Why take the risk using it, when I have 300 quality brand batteries on my hand now? (of course, planning to sell some of them, but I don’t miss sleep over this one battery. I’m using several of the same type in different things here at home, and they work good.)
i have not looked inside a battery bank before but this one dosent seem to have balance leads for each cell so it cant have any kind of balance charging or BMS built in to monitor each cell. looks like it just charges the 4 cells as if they were one combined cell (no balance leads). i know that didnt contribute to you situation but it still makes it a sub par charger imho. i wonder if they are all like that.
I do not know what is more disturbing to me, the fact that this charger/battery had this reaction, or now we all know that you take your pants off and hang them on a chair to charge batteries…… :davie:
Seriously glad you did not get hurt….
With cells in parallel it is not possible to add balancing leads, usual balancing is used with cells in series.
With many cells in parallel you might want do split them in groups, but it has nothing with balancing to do.
LOL, it was in the morning, I had just waken, and was out and checked my mailbox and there the package with the power banks was, so I wanted to test it, sitting in my bed. And you do not want “burning” power banks/batteries in your bed, or in your hands, so the best thing was to trow it away. It just happen to land just under that chair with my pants on. (I’m of course had my sweatpants on) 
This power banks looks like all the different types I have seen, from 4 - 6 batteries. Have some SoShine 4 x 18650 chargers and they have the same layout inside. I like the SoShine and Tomo (think they are produced by the same factory, or one is a knock off, or both are?), but they are in plastic.
Wanted some in aluminum also, that was the main reason i did buy the Xiaomi style PB.
But I think I will continue selling SoShine PBs and then buy original Xiaomi PBs and sell them like they are. If I have not understand wrong real Xiaomi PBs (or products) is good products?
Well for 9$ I bought original xiaomi 10400 powerbank (with 4x2600mAh LG cells), so not everything cheap is poo 
Really good quality stuff, I modded them (very easy job) for 20A current and 4x xiaomi powerbanks in serial for my e-bike project… Why buy fakes if originals are so dirty cheap….
got it thanks hkj. so the parrallel chargers that have individual charge indicators just use 4 individual circits correct ?
Yes.
In power bank you often run all the cells in parallel, because it is cheaper, but a few do use individual circuits. This is only relevant for banks with user replaceable batteries, in any bank with non-replaceable batteries there is no reason to make individual circuits for each battery (They are slightly more safe, but you are way down in minor details).
I know Xiaomi PBs is cheap. I have ordered some on sale and from aliexpress that I have got recommended by other people, that actually have tested them. But the point was to have a PB that I can choose what kind of battery and mAh I wanted to use, so I can give my customers a choice from 4 x 2500 mAh to 4 x 3500mAh. Of course the higher mAh the higher price.
With the original Xiaomi, you have 5000, 10000, 10400 and 16000 and thats that. Also some version you get in different colors, like the 10400. But the 16000 I have seen only in silver, and maybe gold? But with the empty Xiaomi style cases, I could have lots of colors, giving my customers more choices.
Can you check for a short on the powerbank between positive and negative? Multimeter continuity test, usually beeps when there is a short.
I only have a very simple Multimeter, so don’t know if I can test it like you want. Or you have to tell me how to do that. And can you test it without any batteries in the power banks? For I don’t think I want to put a new battery in one of the three remaining bays.
set it to a low ohm setting on your multimeter... that's an easy way to check for shortcircuits
I put my multimeter on the lowest setting on the ohm (200) and when I checked I got readings from 35 to 180. No constant reading, it shifted all the time.
Link or picture of your multimeter? I could point out the setting on your meter. Many multimeters have a continuity setting that beeps when you touch the two multimeter leads / probes together.
You can also use a low ohm setting as Kouryu says but that won’t beep. It that setting, leads not touching should show a “1” on the left side of the meter’s screen. Leads touching will show a low number, example “00.7”
Also can you check the circled areas for damage? Looks like there might be heat damage in those areas. Perhaps burns on the circuit board (or it could just be flux that I’m seeing)? Flux would clean off with nail polish remover or strong alcohol. Burns will not clean off. Slightly melted plastic in the right circle?
How confident are you that you have a genuine, unaltered, original brand-name cell there?
I can’t see the label clearly in the pictures. I do have the impression I see a little groove around the cylinder just before the positive end, which sometimes appears when a protection circuit has been added on then the whole thing shrinkwrapped. If so that would connect directly to the negative plate, and if that circuit is there and overloaded it would burn.
Don’t rely on shrinkwrap labels, we know it’s easy to buy the shrinkwrap labels dirt cheap and put them on crap and sell it as good.