What can cause the screen to become white after starting normally?

On my MacBook Pro Retina 15'' (Mid 2015 - A1398), a "service" store replaced the battery and since then, the screen stopped working normally. It starts almost totally white (however brightness control works). But what is really weird is that if I leave it turned off for 1 or 2 weeks, then it will start normally, image is perfect, and after 10 or 15 seconds, it will turn to white again. Then shutdown/restart won't fix it.

I already tried to open it, disassemble the screen from the computer, disconnect the cable and clean the connectors with isopropyl alcohol, but this did not work. I looked for people having similar issues and it seems to narrow down to the LCD screen or the LVSD cable. Examples:

My display is slowly fading to white. Why?

Why does my screen turn white?

I ordered 2 new cables and am waiting for them to arrive to try to replace it. I am not replacing the screen, but it seems strange to me that after some time without being turned on the screen is perfect again for 10 - 15 seconds. The computer works on an external screen.

Is there a way to be sure it is the cable and not the screen before replacing it?