ASUS Notebook N551JK black screen

[PatrickSteiner]

Notebook
ASUS N551JK-CN173H

Problem
After starting the notebook, the display stays black and the notebook neither boots the OS, nor I am able to get into the BIOS. However I know that the notebook is running, because I can hear the CPU-fan and see the status LED shining.

Attempted solutions
> [Fn] + [F6] Increase screen brightness.
> [Fn] + [F7] Toggle screen on/off.
> Remove SSD, boot, reinstall it, boot.
> Remove RAM, boot, reinstall it, boot.
> Switching RAM-bars (all four possibilities).
> Plug in a second external monitor … no signal.
> [Fn] + [F8] mirroring the monitor … no signal.
> Remove the accumulator, hold for two minutes the power-button, reinstall the accumulator

Annotations
Unfortunately there exists no removable CMOS battery, instead the notebook is using a soldered capacitor and I don't know which one on the mainboard it is.

 

[ffg7]

they don't use a capacitor in place of cmos battery as that capacitor will loose it's charge when laptop is turned off.
https/www.asus.com/support/faq/1005740/

 

[PatrickSteiner]

they don't use a capacitor in place of cmos battery as that capacitor will loose it's charge when laptop is turned off.
https/www.asus.com/support/faq/1005740/

My fault, you are right!
I decomposed the notebook a second time and found the battery on the back side of the motherboard.
However, after swapping the battery the problem still remains.

 

[ffg7]

try this. disconnect the power adapter from laptop. remove main battery not cmos battery. hold the power button down for 20 seconds. re-install main battery. reconnect power adapter & turn on the laptop.