my mac book pro works and worked fine for two years. now all of a sudden it shut-downs automatically and quick. bang! its gone. i couldn't turn it on. I, when connected the power cable it turns on and work fine as ever. if you take the power cable off its gone in a flick of a second. i removed the battery, wiped it and pressed the button below the battery, it says it has full charge. do u think its the battery problem??????? help me pls.