Laptop doesn't boot, need help!

[futuredroid]

I have a weird problem with a Asus K56CM. On Sunday I've installed Kubuntu 16.04 LTS on it. Yesterday morning when I tried to turn it on the laptop could not boot. Not even the post Asus logo was not displayed, but the screen turned on.
So the laptop turns on, the screen turns on too but it's blank.
I tried to remove the power adapter and battery and keep pressing on the power button for a while,(like 50 seconds), multiple times but didn't help.
So I tries to open the laptop's case and removed the CMOS. After that, without putting the plastic lower case back, I turned the laptop on to see if that helped. It did, the laptop turned on booting into the operating system. So I thought that's it, it works. I've put the case back and it didn't work, just like before.
After some tries I've found out that if I tighten some screws which hold the lower case the laptop doesn't boot. Can it be a short? How can I find it? I have a multimiter.
Thabk you!

 

[Laptop_Nerd]

Hi,

There might be a connector or cable that is loose inside the laptop. If you can open the laptop and check every cable and connector if they are seated properly. Chances are there's something touching the inside of the motherboard that causes it not to boot up while the back case is installed.

Here's a video guide on how to disassemble the laptop.

https/www.youtube.com/watch?v=CcMYPHEvMKo