It just happened to me as well.
Niu N1S, 5781Km – battery 103 cycles, usually charged at 25-30% up to 85-95% (never below 20ºC).
On the way back home (temperature ~10ºC) the battery dropped instantaneously from 27% to 0%.It entered discharge protection mode.
I am now trying to charge it back. Let’s see what happens.
Any idea of what could have happened?
Thanks