How to reset ebike BMS

[Eggi]

My mothers ebike had not been used for a while and the battery would not charge.
I opened it up and charged each cell group thru the balance port, so now they are all 4.15 +- 0.05v.
It will still not send power thru the bms, bike will not turn on.
This is what I have tried, disconnected balance port and b+ and leaving bms without power,
shorting b- to bms neg out.
I measure full battery voltage between b- and c-, this could indicate a problem?

 

[fechter]

Unplugging the BMS should reset everything normally. I am not familiar with that particular board in the pic. What kind of bike is it from? I have heard certain Bosch batteries will "commit suicide" and not work again if run too low.

Another thing to try is to charge through the discharge port for a few seconds and see if that works. I have had some that needed this to reset.