How to do when a Mac unbootable and the Home screen displays a blank page directly with a circle?
We must perform the following operation.
Reset the PRAM
Restart the Mac and hold pressed the 4 keys ALT-CMD-PR and keep them pressed until the 5th ‘boing’ (his start). Then release the 4 keys and let the Mac and then start normally.
If it does not work, go to step below.
Repairing system files
To do this, restart the Mac in “single mode” by holding down the Command and S keys (or Cmd andS, as the keyboard) until a black screen with white text appears.
When nothing moves on the screen, make a carriage return (also called “Wrap”): the new line that appears to start now by: / root #
Now type fsck -yf then make a Carriage Return to execute the command.
- note1: case sensitive and spaces
- note2: in single mode, the QWERTY keyboard is therefore to make the dash character (the one before it), it is advisable to take the one on the numeric keypad.
Wait for the result of this command (which can take a few minutes).
As long as it contains “File was modified” then start fsck -yf and make a carriage return.
Type reboot and do a Carriage Return
The Mac will restart normally, then hopefully for you.
If that’s still not OK, so, you need to resume the CD / DVD Mac OS X and restart the Mac by holding down the ALT key until you can select the CD / DVD as the boot source.
A disk repair from Disk Utility will then do.
Resetting the System Management Controller (SMC)
1. Turn off the computer.
2. Unplug the power cord from the computer.
3. Hold down the power button for five seconds.
4. Release the power button.
5. Plug the computer power cord.
6. Press the power button to turn on the computer.
In the age of Mac Power PC, when you had a problem, it was common that it be resolved by resetting the PRAM, a memory containing some settings and could be corrupted causing uncontrolled machine operation . If PRAM still exists on Intel Macs, most of the capitals things are now managed at the SMC.? He manages the following things from Apple.
- The response to the use of the power button
- The response to the opening and closing the cover of the screen of a Mac laptop
- The battery management
- Thermal management
- The Sudden Motion Sensor
- The ambient light sensor
- The keyboard backlight
- Status Light Management
- The battery status lights
- Selecting an external video source (instead of an internal source) for screens of some iMac
If you experience problems with any of these functions, resetting the SMC may resolve it. There are three ways to reset the machine based:
- On desktop Mac, you must turn them off, unplug the power cord and press the start button for 5 seconds. Then, reconnect and restart
- Removable battery laptops, turn off, unplug the MagSafe, remove the battery, press 5 seconds the power button, go back and restart the machine.
- On laptops with non-removable battery, you must turn them off, the CONNECT Magsafe adapter top, and press keys simultaneously (left) capital letter, ctrl, option and the power button a few seconds and release them all at the same time.
We recommend performing a very broadly SMC reset as soon as your Mac seems to have a problem before any other troubleshooting manipulation.