If the battery doesn't want(/show) to charge, sometimes a sleazy trick can do the job: detach it while pc is running on AC and reattach it, sometimes you need to do that more than once. Sometimes after this you gotta keep'em charging some hours and then try again (it all depends on batteries, this is more likely to work on oem equipment).
If this doesn't work try, as Riccardo said, changing the elements, but NEVER EVER fiddle with the electronics... if it goes bad it could set in 1/10th of a second li-ion batteries to go off as a bomb or to catch fire (google a bit for this). Good luck!
