The tablet worked but had a faulty SD card connector.
I replaced it a few times (they’re so easy to break) until I was finally able to replace it with another one.
Only problem is I touched the bottom of the board in the section with the diode painted and accidentally removed a capacitor and a small chip (which I immediately replaced with one from a donor board).
Also I kept the EMMC on (big mistake) and at one point a bowl of rosin solder came out of it (either I fried it or there was a lot of solder inside the metal case from the past connector reworks).
I’ve tried playing around with software (i.e. restoring to factory settings, updating firmware, disabling autobacklight etc) but nothing works. I’ve tried replacing the backlight connector itself with a tested one and I’ve tried 2 or 3 tested screens but still I get a working switch with no backlight.
Now my two main suspects are either the emmc (in that case I wil 99% do less damage if I don’t touch it again), or that area with the diode symbol behind the SD card connector. Does anyone know what is that circuit for? Any other thoughts or similar experiences?