That happened to me too. After recovering 3 batteries, one of them went to red a few weeks later. I think it was due to not leaving the segway plugged in all of the time. I left it off charger for 48 hours, when I plugged back in, one of them turned to red within around 10 minutes.
I tried to trickle charge it back up again (twice), but it just never would turn green. My conclusion is that if you do manage to recover a battery, keep it plugged in and charging all the time after every ride. A recovered battery is an unstable battery and can go bad (turn red) at anytime. I don't think there is anything to troubleshoot here. Sorry man, recovered batteries are living on borrowed time
