my macbook pro completely shutsdown when i take the power cord out and the battery has a full charge. if i try to turn it on, it turns on for a split second then dies. put in the power cord and works fine. ive done all the troubleshooting procedures such as reset pmu and pram etc. i rang applecare and they gave me a service no. and im going to take it to the apple store tomorrow. also when i wake it from a long sleep i get a electric buzz sound which dissappears after a while. and thoughts? thanks