lg g820n can't get into fastboot/bootloader

Question

I have a LG G8(LM-G820N, android 12) on which I am trying to get it into the bootloader but am unable to do so, even though I have been able to do so previously.

1. I tried volume up + power button just does a normal reboot

2. I tried "adb reboot bootloader" just does a normal reboot

3. I tried holding the volume down & plugging the USB in normal reboot; occasionally brings me to a black battery charging screen

• The device is already rooted & bootloader is unlocked.
  
• I have proper driver settings on my PC.
  
• I tried another PC & USB port, but none of them worked
  

Answer 1

I solved the problem myself. Posting for someone who has problem like this, you need engineered abl file in order to get into bootloader!!

rooting guide follow the bootloader unlock steps