If you are reading this guide, it means you might be facing an issue of the Safe Mode loop where your PS4 system only starts in safe mode and you can't boot it from normal mode.
This is not same as infinite restart loop, where you can fix the issue with 5-10 minutes unplug trick.
To fix issue of PlayStation 4 Safe Mode Loop try following:
First call up Sony support and see if they give you nice and easy solution to get your PS4 on normal mode again.
From above screenshot, try option ,3 'Update System Software'. (To get the above menu hold power button on your PS4 for few seconds till you hear the second beep) Update System Software option will download if any new updates are available and install them, after the installation luckily you'll be booted into normal mode.
You can try option 'Restore Default Settings', where your PS4 system will be booted with default settings and you'll need to set the time zone and other startup settings.
Reset your entire PS4 console, if you have uploaded your saves to PSN Cloud Storage then this is good option, although you'll have to go through default startup after complete re-installation.
Hope this guide helps you to get your PS4 back into normal mode.