Just came here to thanks all you guys for sharing your tips. Was able to revive my wife's ebike battery that was left unattended for more than 2 years... First, I tried the wheel backward just to check that the white battery led indicator was at least blinking which it did. Did try the plug/unplug more than 60 times with no success. Green led kept showing and got bored. This morning, did a 40 minutes ride with the front wheel backward. Arrived at home and plug the ebike to finally see the red light on the charger!!! I will now let it charge for a full day and hope everything will be fine. Once again, thanks all for sharing!