Chosen Solution
I have an issue with my mac book pro A1502 which shows in the picture below two vertical lines starting yesterday after replacing the WiFi card. when I tried to connect it to an external display it worked fine. I also tried resetting NVRAM/PRAM and SMC but did not work
hi @pascalito, replacing a wifi card would not cause this type of issue on the display. this looks more like damge caused by dis/re assembly of the unit or perhaps a failing chip on the tab of the display itself. either can occur, however since you have taken apart, i will lean more towards the damage caused by this. i would take the assembly back apart and remove the display so that you able to test it while having access to the display tabs in case this is the reason. you would be able to apply pressure and see when and if the picture clears up.
