The PS3 Slim doesn't get the 'YLOD' as it's motherboard doesn't have the faulty chips that the PS3 Fat had. What you may have is a faulty hard drive though. follow the steps in the video to get into safe mode and make a selection from the menu.
*Warning - You will most likely lose any data on your hard drive before the system runs properly again.
[link|https://youtu.be/TVOJny2FdRM|Using PS3 Safe Mode instructions]