I did not say that.
Nitecore is not a cell maker.
I said I don’t trust Nitecore to use only quality brands. I’ve seen better brands than nitecore (and worse) using dubious chinese cells under the wrapper.
And I said I wouldn’t trust shady chinese cell makers. I very much stick to that as well.
It’s completely useless to know that a Samsung 30Q is rigorously tested, as long as we don’t know what is inside OP’s device.
I doubt Li-Ion chemistry can provide these 9V, so odds are the circuit is broken. What that is doing or has done to the cell, we don’t know until it’s tested. A damaged circuit might constantly drain the cell. Underdischarging will damage the cell.
OP’s device seems damaged anyway. I’d take the device outside the house, open it, remove the circuit and test the cell. Out of curiosity. Just to see which resting voltage it has. Then I’d remove the wrapper to see what nitecore was using. Then I’d bin it anyway and buy me a new Samsung 30Q from a reputable source. Or any other cell or device I want to use. 
