I built my own e-bike last year with a cheap front-wheel drive. I could not get the pedal-assist to run correctly, it went straight up to full speed whenever I pedalled, but the throttle works fine incrementally? So I left it over the winter, now I find I might have ruined the battery! Only used it twice but left on the lounge floor in a corner and did not touch it until today! it's a Green Cell 48 volts 13amph, guess you know what's coming? I cannot get it to charge! Looking online it appears I have ruined it, anyone got any ideas on how to kick start the BMS, please, or is it a write-off?