Try booting into safe mode using these steps:
# If the console is still on press and hold power button until you hear the beep. The console will switch off. Skip this step if it is already off.
# Press and hold the power button until you hear the second beep then release.
# Once you see the PS4 display the safe mode screen with the multiple options displayed on the screen go through each of them and repeat the steps above until you have exhausted all steps.
# When reinitialising console note that this wipes all data on the hard drive.
# If it still does not work. We suspect the hard drive has gone bad and needs to be replaced.