Some lipo balance programs will not balance batteries if a cell's voltage is too low. I've had two batteries do this, in both cases it was when I had not disconnected my battery from my ESC and left them like that for a long time. It's a bad idea, don't do that... Using two chargers. I have balance port plugged into my LRP charger set to balance->view mode and the deans plug is plugged into my old charger in NIMH mode and set to 1.0A. Then I monitor each cell's voltage level (don't leave this unattended!!!). To get them both into the 3.3 -> 4.2 range. If needed I let one go past 4.2 in order to bring the lower voltage one up enough to get into balance mode. Or discharge it again to bring it down while still getting some voltage into the low voltage cell. Also, use some form of lipo charging bag for safety.