Question ASUS ROG GX800VH Black Screen, Fan Spinning and Numlock light on

[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. Resitted all 3 SSDs. So far nothing worked. And in google there's not much info about gx800vh. PLEASE I NEED HELP !

 

[helpstar]

did you try an external monitor?

 

[Sharpin]

did you try an external monitor?

Unfortunately, I don't have a external monitor. Also, my usb keyboard lights up and turns off and my laptop's keyboard lights up but unresponsive (Capslock doesn't light up when pressed). Only the Numlock light remains ON.

 

[helpstar]

you can use a TV instead

is the charger light on while charging?

 

[Sharpin]

you can use a TV instead

is the charger light on while charging?

Yes the charge light is on, fans spin.

 

[Sharpin]

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.