White screen but is working on external monitor

The display is working before but this morning as I was turning it on, for the first few seconds it is displaying the logo correctly but then some weird lines took over the screen then it turned white. I plugged it into an external monitor and it is working just fine (which means the GPU ain’t faulty) presumably that the LCD and its cable may have been damaged through wear and tear. So I replaced it with an LCD from a MacBook of the same model and the problem still persists. Is there a component on the motherboard responsible for this display failure?

The screen during boot (It also has a display after waking from sleep)

The screen after a few minutes of warming up

I was not able to take a picture of the lines appearing on the screen (my camera can’t pick it up)