My macbook air, mid 2013, needed its battery replaced. So I bought the battery off of amazon and was able to replace it easily. However I experienced a problem when I turned it on as there was no audio. Can't change the volume or adjust the settings it just gives me the no symbol. After taking the battery out and puttimg it back on again to see if that would fix my problem, the fan started blowing really loudly as soon as I started up the computer. On top of that the light no longer appears on my charger. I even put the old battery in again to see if that was the problem and nothing changed. I was thinking I might of accidently damaged the audio cord, but i want to make sure before I get a replacement. However I don't think that explains the fan and lack of light on my charger.