First I would do a SMC reset to make sure the SMC is working properly. Follow this Apple T/N: [https://support.apple.com/en-us/HT201295|Resetting the System Management Controller (SMC) on your Mac].
You could also give this little gem a try: [http://www.coconut-flavour.com/coconutbattery|coconutBattery] it's a free app that I think does a better job in showing how things are doing.
Then tell us if the SMC is reporting the battery now. If not the charging control logic (SMC) has problems and you still may need a new battery as well. But you'll need to get the main logic board repaired first.