Macbook A2337 820-02016 PPBUS 12.3V

[Instafixx]

PPBUS is at 12.3V and fluctuates between 12 to 12.3V.
Without Fuse its stable 12V stable at PPVBAT.

3V8_AON present.
5V_S2
3V3_S2 and other rails are missing. No Shorts.

Thermal scanning shows L7800 getting hot but no shorts.
Also heat spikes and goes down continuously at U5200 and RC212/3

Can it be a UC710 issue or U8100 ?

 

[Instafixx]

I replaced U7700. But still L7800 heats up.
With L7800 connected PP3v8_aon_vddmain is 1.5V
With L7800 removed its 3.8V