Did you boot to Recovery HD and Repair Permissions?
Reboot into the Recovery HD by choosing the ‘Apple‘ menu > Restart, then hold down the ‘Command’ + R’ keys on the keyboard during the start up process. When you see the Apple Logo you can let go. When the machine boots you may have to choose your language then you will see the OS X Utilities screen. Select the Disk Utility and then select Continue. Then in Disk Utility select Macintosh HD in the left column (if there are two with that name or it is named something else choose the first indented item) select the First Aid tab if it is not already selected, then click on Verify Disk on the far right. If that says “OK” in green type then select Repair Disk Permissions. If it is not ok let me know.
Was Verify Disk ok then you Repaired Permissions?
OK do that again but this time Reinstall Mac OS X.
Do you have a backup?
Let me know about the backup... Try this to clear some things:
Restart the computer and immediately hold the Shift key until you see the Apple Logo. This is called Safe Boot and it will attempt repairs. If you get to the login screen put in your user/pass, if it boots up, restart the normal way. Let me know what happens after.
If you want another technician then I just opt out you don need to start over... good luck
Hello there! Sounds like their might be an issue with your user please follow the steps below to create another user then we can verify if you can log into this user.
Turn off your Mac.
• Turn it back on and immediately hold down the Command(Apple) and S keys together for 10 seconds to boot into Single User Mode
• When you see the text prompt, type in the following terminal commands to create a brand new Admininstrator account (hitting return after each line). Also, note down the spaces between the commands, like a space between mount and -, space between -uw and / etc
mount -uw /
shutdown -h now
After rebooting, you should be able to login to a brand new Administrator account.
No worries i will forward this to customer service :)