Problem is a balance charger will error when it detects the low cell and not go into the charge mode.
A balancer would be counter productive because it will want to bring the other cells down too.
In my case I was able to bring them back
-=WARNING=- If you try this you are doing so at your own risk for fire and other lipo and charger safety issues=- By carefully charging the whole pack through the discharge plug to a little over 9v using the lead battery setting on a multi-charger. Once the low cell is high enough to be recognized by the normal balance charge setting on the charger, just used them normally. -=WARNING=- If you try this you are doing so at your own risk for fire and other lipo and charger safety issues=- I won't pretend that this brought my batteries back to tip top condition, but since I had only a few and these were used for combat it brought them back to good enough condition and better than toss in the trash condition