MacBook Pro 15" (late 2013) logic board repair resistor

It's very difficult to troubleshoot a complex circuit board without a schematic. They are available if you look around. Louis Rossmann (https://www.youtube.com/channel/UCl2mFZo...) has a great channel for repairing MacBooks.

When it comes to water damage, always start by looking at the areas that are corroded and try to identify bad components. What often happens is that main power rails get shorted to ground due to the liquid. This can cause local or extensive damage. Capacitors are susceptible to damage and can short a power rail. However, sometimes the problem is within the power supply chips themselves (LDO).

Get the schematics, give it a try...