Batteries Plus, or anyplace like that, will take the discard cells.
DO NOT toss it in the saltwater solution like Robert B said! BAD ADVICE!
I’d remove the wrapper and cut the protection circuit, see if it stays a problem with the protection circuit disabled. If it seems fine then I’d remove the protection stuff and re-wrap it, keep an eye on it in use in a regular flashlight and see how it goes.
If the resting voltage is 9.68 volts like the op stated above what use is it. If he sticks it in a flashlight it could fry his driver or give to much current from the higher voltage and go “POOF”.
I=V/R
His over twice the normal voltage. You might try removing the PCB but I don’t think the circuit can boost twice the voltage. Far as I know it’s just a simple controlled FET switch.
Single cell XHP70 light? 
That will work direct drive. Might be the worlds brightest single cell XHP70 for a few seconds.
Not sure I’d consider Nitecore shady. Do you have evidence of any shady issues Nitecore has engaged in?
As far as that goes, it’s far more likely to be a fake Nitecore. That is, some Chinese guy is recycliing used laptop batteries and has 200,000 Nitecore wrappers to use up. Nitecore chargers have been and are being counterfeited. (see links below) The OP received it as a gift so we cannot even authenticate the purchased location.
https://budgetlightforum.com/t/-/37563
http://www.candlepowerforums.com/vb/showthread.php?424302-Fake-Nitecore-Chargers-even-in-very-big-stores-D4-and-others
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. 
i still fail to see how a cell goes to 9.xx v from a charger fed from 5v and through a linear regulater charging chip.
unless its plugged into usb3 on a pc or fancy phone charger and something went wrong there.
but these are long shots.