Hi, made a complete nob of myself this week end 
I was testing volts on my xtar 18700 batteries… one of them i accidently shorted, it got hot fast then when i realised what i had done voltage dropped to 2.07
Apparently my charger can repair this it claims in the instruction booklet so i put the battery in id shorted and got a red and green flashing light…… normally its red when charging then turns green.
Anyway it eventually turned green and voltage said 4.07 although the other charged xtar measures 4.17.
So have i broke this battery?? is it still safe im wondering more than anything?? And why wont it get up to the usual 4.17 now??
Im using an Xtar wp2 ii charger by the way…… which definatly charges both batteries to the same voltage usually, i know some people have had problems with this charger.
The cell got hot? That would be a case of a not-working PCB..
I have read of PCBs not shutting down completely, so you would still see some voltage, but the value can be way off. The fact that it only goes up to 4.07V now could be caused by a higher internal resistance caused by aging through shorting.. but others know better about that.
Long story short: if the cell got hot, I would dump it. No reason to risk anything for a few bucks.