Starting the PS4 in Safe Mode
Turn off the PlayStation 4 by pressing the power button on the front panel. The power indicator will blink for a few moments before turning off.
Once the PlayStation 4 is off, press and hold the power button. Release it after you've heard two beeps: one when you initially press, and another 7 seconds later.
Connect the DualShock 4 controller with the provided USB cable and press the PS button on the controller.
Safe Mode Options
The following options are available in Safe Mode:

Restart System - Ends Safe Mode and restarts the PlayStation 4 normally.
Change Resolution - Changes the screen resolution to 480p when the PlayStation 4 is restarted.
Update System Software - Allows the PlayStation 4 to update the system software via Internet, USB Drive, or Disc.
Restore Default Settings - Restores the PlayStation 4 to the default factory settings.
Rebuild Database - Scans the drive and creates a new database of all content.
This operation may take a long time depending on the type and number of data items.
Initialize PS4 - IMPORTANT: All data and settings will be lost by performing this step.
Deletes all user data and restores the PS4 to as if it just came out of the box. This option is the same as [Initialize PS4 ] in the (Settings) menu. System software (firmware) is not deleted.
Initialize PS4 (Reinstall System Software) - IMPORTANT: Deletes all information on the HDD, including the System Software. A message that states a USB storage device containing the System Software must be connected, is displayed. Then you can confirm the selection.