820-4924-A Shows 4GB Memory Installed Instead of 16GB

[bcherdak]

Hi guys, got a 2015 macbook pro retina here and after repairing liquid damage computer fully passes "D" test diagnostic but is only reporting from "About My Mac" that it has 4GB ram installed on 2 banks.

Looking up in GSX it shows that it comes with 16GB of ram, I am guessing that 2 of the banks are not being activated or do not have power going to them.

Has anyone seen this issue before? Do I reflow RAM Modules? Any measurements you would like me to take?

Photos attached.

 

[2informaticos]

Did you take photos before cleaning the board?
Heat affected chips with good flux, ultrasonic board and pray.
Maybe is better to reball non-working chips.

 

[bcherdak]

Did you take photos before cleaning the board?

Corrosion was around LCD connector and JTAG connector in the center,

Removed JTAG and also replaced LCD connector.

"Maybe is better to reball non-working chips."

How do I know which chips are not working, is there a voltage measurement I should take to see which ones are not turning on/being used??

Also, there are 4 chips on the board for 16gb ram, but shows 2 banks being used, doesn't that mean that 2 banks should equal 8gb total as each bank is 4gb?

 

[bcherdak]

RAM Has been reflowed

Did not solve issue. then I reballed the ram with a stencil and that did not also solve the issue,

Are there any voltages I should check to see if voltage is going to it?

 

[2informaticos]

Try BIOS, just in case...