820-3435-B not powering on. PPBUS_G3H only 3.28v

[joshAU]

Hi again.
I have Macbook Air that came in reported not turning on.
Gets a green/orange Magsafe LED but no fan spin or other sign of life.
Tested with known good charger - same.

Very slight water ingress - literally a few dots only on the top side of board.
A few tiny signs of corrosion near:
C5514 (just above u5000, but no signs of corrosion on, near U5000 at all).
C2971,
R8154.

Cleaned.

Noticed Q7130 was getting too hot to touch.
Replaced and no longer getting hot.

ALSO, PP3V3_S5 MEASURES 0v.
However PP3V3_S5_AVREF_SMC is 3.3v

Other voltages:
PPBUS_G3H = 3.28v
PPBUS_S5_HS_Computing_ISNS = 3.28v
PPDCIN_G3H = 15.14
PP3V42_G3H = 3.42
PP5V_S5 = 3.21

Thanks for any help you can provide.

 

[2informaticos]

Post U7100 voltages; pins 1, 2, 3, 6, 9, 12, 13, 14, 15, 17, 19, 20, 27.
Replace C7125, just in case.
Check all solders and traces around ISL6259.
Also post exact resistance between pins 17/18 and 27/28.