MacBook Air A2337 820-02016 No Power at 5V-0.42Amp

[saisoni20]

I've got an A2337 820-02016 that has no power. No sign of liquid damage and no obviously damaged components.
U8100 is getting HOT.
What could be the issue? Is it bad u8100 or any other specious component which is causing U8100 to fail?

[mon2]

What is the voltage to ground of PPBUS_AON @ F5200?

[saisoni20]

mon2
PPBUS_AO is 12.30V

[mon2]

What is the voltage to ground for the following?

I2C_SMC_PWR_3V3_SDA
I2C_SMC_PWR_3V3_SCL

[saisoni20]

I2C_SMC_PWR_3V3_SDA - 0V / 350K respect to ground
I2C_SMC_PWR_3V3_SCL - 0V / 350K respect to ground

[mon2]

No short on these SMBUS 3v3 pins but also no pull-up voltage to park these open-drain lines.

See attached.

Confirm if you have a Vin and also the ENABLE (VEN) pin voltage on this LDO.

[saisoni20]

PP3V3_AON - OV
PP3V8_AON_VDDMAIN - 3.7V

[mon2]

Check if there is a voltage on PP1V8_AON_MPMU. If not, remove all power, measure the resistance to ground of PP1V8_AON_MPMU.

[saisoni20]

PP1V8_AON_MPMU -0V and 0.8ohm respect to ground.

[mon2]

Something is wrong here. If you have an adjustable power supply, consider to inject 1v (not higher) onto this same rail. Then hunt for who is heating up. If you do not have a thermal camera, the pharmacy grade alcohol from Costco works well. We use that primarily for cleaning but also works to test for heat signatures.

[saisoni20]

I have checked by injecting 1V. U8100 is getting hot.