1. Turn off the console completely.
2. When the PlayStation 4 is turned off, hold the power button. Release it when you hear a beep after 7 seconds.
Plug the DualShock controller 4 with the included and press the PS button on the controller to activate USB cable.
And you will be ready to use the Safe Mode or Safe Mode.
Safe Mode options
In the secure mode, the following options are available:
Reboot System - Exit the Safe Mode and restart the PlayStation 4 system normally.
Change resolution - Change the screen resolution to 480p PlayStation 4 when the system reboots.
Update system software - Allows the PlayStation 4 system to update the system software via the Internet, using a USB device or a disc.
Restore Defaults - Restores the PlayStation 4 system to the factory default settings.
Rebuilding database - Explore the unit and creates a new database with the content.
This may take several minutes depending on the type and amount of data.
Initialize PS4 - IMPORTANT If this step is followed all data and settings will be lost.
Deletes all user data and reset the PS4 system to the state it was out of the box. This option is the same as [Initialize PS4] menu (Settings). The system software (firmware) is not removed.
Initialize PS4 (reinstall system software) - IMPORTANT: Remove all hard drive information, including system software. A message prompting you to connect the USB storage device containing the system software are displayed. Then you can confirm.
You shall not normally use the secure mode throughout the life of your console but if you receive the "blue light of death" or are you off by a power failure while the actualizáis or any failure like that this will be your salvation.