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This usually happens if the system files are corrupted or if there is any issue with the hard drive.It could be the hard drive that is failing. We can run Disk Utility and see if it works or not. Turn off your Mac by holding down Power button for 10seconds. Then turn it back on and immediately hold down Command and R keys at same time for 20 seconds and this will boot your Mac to the Mac OS X Utilities screen. From there, click Disk Utility. Select your hard disk at left column(Macintosh HD or hard disk name). Then click Verify Disk (under First Aid). If asked to repair, click Repair Disk. Then click Repair Permission.
If you are using latest Mac OS X El Capitan, then you will not see Repair Disk option in Disk Utility. Instead click First Aid button and run it. Repair if asked.
Then restart from Apple menu. If that didn't work, then turn it off. Turn it back on and immediately hold down Command, Option, P and R keys at the same time for5seconds, then release the keys and immediately hold down Shift key for20seconds. Does it boot into desktop ?
Please let me know if that didn't work, so we can continue troubleshooting.
It souds like the hard drive is failing. Can you restart and try to reinstall OS X ?
You can reinstall your Mac OS X. Reinstalling OS X won't delete any of your files. It will just replace the corrupted system files with new one and that should fix the problem unless it is hardware related.
Hold down the Power button for 5-10 seconds to turn off your Mac. Restart your Mac and immediately hold down Command and R keys at the same time for 15 seconds and this will boot your Mac to the Mac OS X Utilities screen. From there, click Reinstall Mac OS X. Then follow the instructions to reinstall your Mac OS X.
If that didn't work,then restart your Mac and immediately hold down Command, Option and R keys at the same time for 15 seconds and this will boot your Mac to installation screen. Follow the onscreen instructions to reinstall.
Please reinstall the OS X. Disk Utility may not be able to detect physical failure in the Hard drive.
Sounds like you are on older version of OS X and to reinstall, you need to know his Apple ID and password. It is asking for verification purposes. You can't over ride it.
Turn off your Mac. Turn it back on and this time hold down Command, Option and R keys and this will boot into Internet recovery. Does it allow you to reinstall from there ?
If it is showing globe and loading bar, then it may take from 5-30 minutes normally. It may take more to load if your internet connection is slow
Give it a few more minutes.
Don't turn it on yet. Try the following first
Shut down the computer.
Plug in the MagSafe power adapter to a power source, connecting it to the Mac if not already connected.
On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
Release all the keys and the power button at the same time.
Press the power button to turn on the computer.
Then reset the PRAM and NVRAM of your Mac. Follow the steps below;
Shut down your Mac
Restart and immediately hold down Command-Option-P-R keys at the same time
Hold the keys down until the computer restarts and you hear the startup sound for two or three times.
Release the keys and let the Mac bootup.
After this restart and boot into OS X Utilities holding down Command, OPtion and R
I'm sorry, since your Mac is not booting up I will not be able to connect to your Mac and fix it from here remotely. So please ignore that offer.
Is it not loading to OS X Utilities screen when you hold down Command, Option and R ?
If not, then turn off your Mac. Turn it back on and immediately hold down Command and V for a few seconds and this will bring a black screen with letters. What does the last line says ?
I'm afraid this is an hardware issue. It is the possible that the internal hard drive is failing or it could be the connection or internal board and that is what is preventing it from loading internet recovery. You may need to take it to the Apple Store to get the drive replaced. The hard drive replacement may cost up to $120 GBP
But before I send you out to do that, let’s check every possibility to be sure it isn’t something else in an effort to save you from that expensive repair. Try the above steps and let me know the results please
Thanks. I hope it is not hardware related. Good luck