MacBook Pro A1502 2015-2016 Not turning on (low PPBUS G3H voltage) repair

Problem description
Power Failure with Low PPBUS_G3H Voltage (1.7-4V) Instead of Expected 12.56V; Potential Liquid Damage.

Symptoms

 * Not turning on.
 * Low PPBUS_G3H voltage
 * possible corrosion/liquid damage

Solution
In the event of liquid damage, recommended troubleshooting steps include disconnecting all components, thorough cleaning of both sides of the circuit board, and conducting a reevaluation.

The issue may stem from a defective U7100 ISL6259 IC, possibly leading to a short-circuit of the current sense resistors R7121 and R7122 to ground through the U7100.