Can you tell me the version of MAC which is installed in your macbook ?
OK, you can get the instructions to check the version of MAC from the link below. Please check it and let me know.
Did you get this information, after following the steps below from that link ?
From the Apple () menu, choose About This Mac. Your version of OS X appears directly below “OS X”:
Now, I facing another problem, there is no such model like MX 6820 , can you tell me the correct model no.
Do you still need help with this issue