asus ASUS ROG GX800VH Black Screen, Fan Spinning and Numlock light on. No POST with battery and Black screen when AC plug removed.

[Sharpin]

My Asus ROG GX800vh laptop, which I have been using for over a year

Last night I used all fine and shutdown as usual, came from office today and started it up; laptop turns on, fans spinning but no display, not posting and numlock light is on.

Things I've tried: Opened laptop and 2 out of 4 rams to see if it boots, cleaned rams and ram slots. Not working.

Also, getting access to 2 of the ram slots are tedious thing. Resitteed all 3 SSDs.

So far nothing worked. And in google there's not much info about gx800vh.

 

PLEASE I NEED HELP !

[Sharpin]

Update on Jun 21, 2023

 

The issue with no post is resolved when I took out CMOS battery and removed the battery then connected charger and powered it on. Laptop did power cycling few times and then post but after loading windows I got a black screen with login screen running,
I force shutdown few times to get to windows repair and then proceed to Safe Mode. In Safe Mode I DDU my Nvidia display driver and restarted. I login normally then proceed to install Nvidia Driver. But during driver intallation I get Black screen with windows running in the background. I tried a couple of times but same reuslt.
Also this laptop had 2 Nvidia GTX 1080 in SLI and in Device Manager one of the GPU shows Yellow error icon. And when I try to open Nvidia Control Center, I get an error message saying no display is attached to the GPU.

 

[Sharpin]

Update: Laptop ran alright for two days, i shutdown normally and the next morning again laptop boots up to windows with black screen. I can see the BIOS ROG logo and as soon as it is about to go to login screen, I get black screen. Force shutdown, RTC reset by holding power button for 40 seconds doesn't work. I can only boot into windows to safe-mode with display though system repair process. DDU the display driver and boot normally into windows with Microsoft Basic Driver. When I try to install Nvidia Driver, during driver installation during second screen flicker I get black screen with driver install fail sound and black screen. Force shutdown and power up doesn't resolve. Safemode > DDU > windows boot works. However, doing DDU and Driver Install suddenly successfully installed the drivers with no black screen. After successful driver installation, I ran GPU-Z and all GPU information shows normal, I even ran Heaven Benchmark for half an hour and works fine. Then laptop runs normally for two days and same thing again.
Yesterday I found out the laptop doesn't POST using battery and fan spins fast with keyboard backlight on. Then when I connect the AC plug, it boots up normally after a coupe minutes with no POST. Also, If I remove AC while the laptop is running, I get black screen with windows running. I cleared CMOS, changed CMOS batter with a new one. This issue repeats. Battery charges and discharges fine btw, also battery health is good.
Note: ASUS Gaming Center gives me a Falied Overclocking message, saying BIOS>Defaul> Save, which I did. Even though I clearly didn't overclocked anything. (ASUS ROG GX800VH does overclock on its own when docked but even without docked I get Overclock Failed error message.)
I want to take it to a repair shop but I am scared that they would try to repaste ICs without care and nuclear the board. It's Bangladesh after all.

Any suggestion would be appretiated. I don't understand I'm not getting help from any forum sadly.