Dell XPS 15 9500 doesn't power on

I've seen some other posts similar to this in the forums, but none of the solutions written there worked for me. 

The problem I've been having with my XPS 15 9500 is that whenever the AC adaptor is not plugged into the laptop and the laptop goes to sleep (basically when I bring my laptop outside and I close it), the laptop then refuses to turn back on the next time I open it. I click the power button, and the keyboard light turns on, and the fan turns on, but the screen stays black. The fan is always constantly turning on and off.

Long pressing the power button to reboot doesn't work. 

Pressing 'D' as I turn on the computer does the "white red blue green" reboot thing, but even this doesn't let the computer turn on. 

Sometimes the dell logo appears, but then it quickly disappears, back into a black screen. Whenever this problem happens, I also can't open up BIOS settings by pressing 'f12'.

The only way the laptop turns on again is to connect it to an AC adaptor and wait about 30-60 minutes for it to randomly and naturally reboot itself and turn on.

However, this problem doesn't only happen when the laptop is not connected to the AC adaptor. Sometimes, I'm just using the laptop at home, connected to the AC adaptor, and the screen completely freezes. And this screen freeze is not just a normal screen freeze. I can't do anything to fix this screen freeze other than to long-press the power button and reboot it. I actually tried waiting for like 6 hours once, but the screen is still frozen. Even if I do 'windows+ctrl+shift+b', the screen doesn't get fixed. Even if I click the power button, the computer doesn't turn off and the screen keeps displaying the frozen screen. The only way to stop the screen from freezing is to long-press the power button to completely turn off the laptop. 

And then guess what? The laptop stops turning on again. 

Basically, even when I'm at home using the laptop connected to the AC adaptor,  I'm in a loop where the I'm using the laptop, it freezes, I turn it off by long-press power button, the laptop stops turning on, I have to wait for it to turn on by it self by waiting 30-60 minutes, the laptop turns on, I begin to use it, then it freezes, ......

Here's what I think is a clue to the problem I'm experiencing: 

I checked the logs on BIOS, and whenever the laptop doesn't turn on, it's written "LED CPU FLASH ON ON". So I'm guessing it's an issue with the CPU. I'm not a computer expert but yeah I really need this to be fixed and I want to know if there are others who have the same issue. 

I'm pretty sure I'm going to have to send my laptop to Dell for repair, but yeah. I'm just pretty annoyed the past few weeks cuz I literally can't use my laptop at all. And I'm in the middle of my exams. Yeah. Sorry for the long text.