820-00165A Liquid Damaged Doesn't start with i/o board plugged in

[CRC2018]

Got a Macbook Air A1466 liquid damage job in today 820-00165A board. Have cleaned it up and fixed the following issues:
1) C7136 completely exploded and burned PPDCIN_G3H_CHGR to ground inside the board - have done some digging around where C7136 was and cleared this short
2) Backlight feedback to LP8550 was broken next to L7701/D7701- have repaired this with a jumper wire.

The issue is board will start fine without the left i/o board connected, it runs gives backlight etc. If the left i/o board is connected I get the orange light and it wont start - tried with known good i/o board, known good connecting cable and known good battery - it wont start at all.

If I were to connect the Left I/O Board after the fan starts to spin after applying power from charger with battery connected I just get the display with the battery charging symbol then it powers back off and no reaction to power button - power button is working normally when left i/o board isn't connected.

PPBUS_G3H is giving 8.6V as I would expect when the orange light is lit.

I know these boards wont normally start without the battery being plugged in so I'm thinking maybe this is an issue with the battery circuit.

 

[2informaticos]

"I know these boards wont normally start without the battery being plugged in"
I never faced with such issue on these boards.

Check basic signal for power on sequence with LIO board connected.
Inspect J9500 pins for corrosion.

 

[CRC2018]

Interesting you should say that - for the past couple years i've never found an 820-00165-A which will start without the battery when the left i/o board is attached - they will start when the i/o board is not connected usually just like this one!
J9500 is clean - there was 0 liquid damage on that part of the board, main areas of liquid damage were around the display connector and around where the trackpad plugs in - Q7130 area.

 

[2informaticos]

Are you using original Magsafe 2 charger???

 

[CRC2018]

Thats a good question - i'm not 100% sure it is original but it certainly looks it - it's an 85W one.

Found out why it wasn't starting eventually - it was R5501 not connected on PPBUS_G3H side. Now i've got another issue that the board appears to start but after I shut it down and leave it for a bit it won't start up again and gives the "I need charging" symbol (on battery) or the "charging" symbol on the screen (on charger) - battery is at 100%. If I do an SMC reset it'll usually then start up and shows the battery at 100%. I've got a battery on order to test so i'll report back if that fixes it.