Hey.
I have a macbook pro 2015 model with the 820-4924 motherboard. It’s been dead for years. After checking with a multimeter, there was no voltage running through it even when plugged in. After looking into it I saw a shorted/burnt looking DC inboard, replaced it with the correct part (820-3584-A) and it still didn’t show a charge light, but this time I had the following voltage readings running through the motherboard up until the SMC chip:
16.5V on the DC inboard’s 5 pin.
3.5V on the battery’s 9 pin.
3.46V on components around the SMC chip (I’m guessing components related to the chip but I’m unsure).
Everything after the SMC chip doesn’t get any power and the SMC chip and the entire motherboard looks pristine after deep visual inspection.
After inspecting the laptop more I saw a bit more burnt/shorted discolouring on the I/O board.
It might be worth to note the laptop previously had speaker issues (distorted sound) that weren’t resolved.