Help with Schematics - Motherboard model number -820-00045

Hello all

I was wondering if somebody could point me in the right direction

I am looking into going into micro soldering, now that I feel I can do screen replacements etc to a high degree.

I have a motherboard from a A1534, when you plug the usb-c charger into a usb-c tester and then plug the tester into the MacBook nothing happens on the tester screen.

I then looked into hours and hours of videos on how to test the motherboard.

I have a couple of questions and i hope somebody can point me in the right direction

1) How can i test the usb flex (with a multimeter or otherwise) to make sure it is working before i buy another one and find it makes no difference

2) Ive been looking at the schematics for the motherboard and can see a section for power rails, pp5g3h pp3ve etc etc, is there some order they should all be tested in?, and do they all have to have a voltage measurement test or do i have to see the resistance readings for them

So in the case of pp3v3r3_aon, i plug the usb c cable in, i then turn my multimeter to 20V DC and then place the black probe on ground and the red probe on one of the caps that correspond to pp3v3 but i get nothing, a resistance measurement gives me around 40ohms……………Am i doing this correct? if so do i do the same for all the power lines or are there some specific ones i have to concentrate on?

3) Some of the the other forum’s etc mention checking the power rails to ground, is this the same as checking the capacitors that correspond to the rails or is it something else?

4) Finally where do you start on how to read the schematics and what all the lines do, is that just a experience thing or is there somewhere can refer to?

Thank you for your help and guidance

Regards

Ali