i have 2 hobbycity LiPo 2100mah, 30c, 7g batteries. one charged no problem on my polycharge4. the second went through the initial startup sequence but the indicating light went from solid green to 4 red flashes. indicating a fully charged 4 cell battery. i measured the battery voltage and got a reading of 10.6V. i dont believe the battery to be over-discharged because i understand that a cell must be below 3V to be in this condition.
any advice would be great, if theres any way of rescuing this battery as replacements are costly.
thanks.

Are you balancing the battery?
It is possible for a single cell to be overcharged or over discharged preventing it from charging normally.
There are a couple of good lipo balancers for around the $25 price.
http://www3.towerhobbies.com/cgi-bin...&I=LXMRZ9&P=ML
http://www3.towerhobbies.com/cgi-bin...&I=LXMGS7&P=ML

Might as well pick up a lipo sack while your out shopping. It could save you a ton of problems.
http://www3.towerhobbies.com/cgi-bin...?&I=LXSEA5&P=M