when LITHIUM BIONX battery voltage drops below 10V BIONX charger no longer can recognize it and will not start charging.
YOU have to open battery and rise voltage manually SLOWELY but steady to at least 30V /again I talk about LithiumBIONX/
The way to do it is to connect wall adaptor with DC output at least 40V and 0.5 Amps directly where battery connects to BMS, simply to charge outside BMS. It must be DC output adaptor /check label on it/ not AC output.
You must monitor voltage every couple of hours not to overcharge.
Again you want to do it slowely so no more than 500mA /0.5A/
instead of wall adaptor you can use lab power supply with current udjusted at no more than 500mA.

Bionx battery is 36V so I imagine 12V charger would have to be used to charge 3 section of battery seperate.