820-00840 video problem

[Kyle93]

Arrived with no liquid damage or visible damage on board. Completely black screen on internal screen and when plugged into external only half the image appears see attached picture. Tried known good screen but still black

what should be checked first??

 

[2informaticos]

Do PRAM reset 2-3 times.
Test again external video, disconnecting LCD assembly.

 

[Kyle93]

No changes after pram reset. Still no backlight or image on internal. External still half black as in picture. Tested with LCD assembly disconnected

Apple diagnostic says there may be a issue with the display VFD001

What next?

 

[Kyle93]

After login the 1/2 black screen disappears and the whole screen shows normally on external

 

[2informaticos]

Still nothing on internal LCD, inside macOS?

Do you get 3V3/5V_S0SW_LCD at least in the first few seconds, when chime?
If not check disconnecting internal LCD.
If yes, DP_INT_HPD should go high at same time; ONLY with LCD connected.