Boot to recovery mode by holding CommandR right after starting your Mac before the Apple logo appears. (When it is all up and running, create another fully cloned OS drive, as part of disaster recovery. Open the Fastboot folder, hold down Shift, right-click anywhere blank, and choose Open command. Click the operating system that you want to repair, and then click Next. In most Android devices in the recovery mode you can: fastboot the device, find more info about it, wipe personal data, reset cache partition, update system, check root integrity and accomplish other advanced operation. The recovery key is the only way to unlock the machine if the machine is in a recovery mode. Connect the recovery drive and turn on your PC. iTunes should now inform you that it has detected an iPad in recovery mode.

One time-honored trick to recover from a white screen is to boot into Safe Mode.Steps to Enable USB Debugging Using Recovery Mode.Click Repair Your Computer and then select the operating system you want to repair. Disable Daemon, Agent and Phone home Symptoms. Click on the Start Menu and click on the Power icon. However, for unsupported devices, here we have listed the unofficial custom recovery builds.Release both of the keys when the System recovery screen is displayed. Wait 2–5 minutes for the update to complete.

You can now go about restoring the device. Give root password for maintainence (or type control-D to continue): I have tried all the above commands but nothing happens. Keep holding down the shift key until the boot progress indicator shows up. It will ask you to confirm by pressing the RECOVERY BUTTON again.

Team Win Recovery Project or TWRP Recovery is a useful and popular custom recovery, which is open-source software.

From the list of options, select 'Troubleshoot' > 'Advanced options' > 'Startup Repair'.

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