Lishui are OEM only so you won't willy nilly pick one up, you can try Woosh bikes as they use them all the time. The issue though is that they are usually programmed to the suit the motor they are used for and parameter aren't changeable like KT.
Have you checked battery voltage at all with a meter ?
Also possible the display/lcd is at fault, to rule out a faulty display you can short out the wires on the connector but we would need to see a pic of connector/wire colour.