How to fix intermittent backlight on iPad Mini?

I have fixed a dead backlight iPad Mini by changing the 4R7 coil and the diode next to it. It worked fine afterwards, but after a few minutes of use the backlight died and didn't come back. Even after a hard reset. What I did is open it up again, remove the diode (thinking it was faulty as it didnt read continuity either way) and install a new one. It worked again for a few minutes straight (maybe 5 minutes) and the backlight died again.

Unfortunately it was not me who had it in my hands both times so I can't tell if it flickered or not, its my friend's kid's tablet.

Any advice? Thanks