MacBook Pro A2159 Not turning on, fluctuating current draw 0.03-0.1A at 20V repair

Problem description
This issue is often caused by a short to ground on a sub-rail, which can be accurately detected with a high resolution thermal imaging scan. Low resolution thermal imaging may not reveal the subtle signs of a small shorted component, making it a less reliable diagnostic method.

Symptoms

 * No power
 * No fan spin
 * All voltages missing

Solution
If the issue has a single, specific solution, provide it in this section and delete the sub-headers below. Otherwise, if there are multiple potential causes for the problem, outline the process of identifying the root cause and offer corresponding solutions below.

Diagnostic Steps

 * Perform High Resolution, High Sensitivity thermal imaging of the entire system board.
 * Low resolution thermal imagers will likely not pick up the subtle temperature changes failures like this often present with.
 * The failure will often present as a component quickly heating up and cooling down in sync with the amperage changes; Occasionally, you will find a resistor heating up/cooling down in sync with the amperage changes.
 * The short is likely caused by something on the output side of the resistor.

Repair Steps

 * Remove and Replace the shorted component based on thermal imaging findings.