820-01949 - No signs of life after screen replacement

[ronaldo]

The Mac came in for a screen replacement.
I've replaced the screen it stops working.

Trackpad clicking in a loop. I've replaced screens on a hundreds of Macs and never had this issue.
Getting 20V and 0.0230A

LogicBoard was stand-alone.
All AWAKE and SLP are cycling every 14 sec

PP1V2_AWAKE - 1.2V
PP1V8_AWAKE - 1.8V
PP3V3_AWAKE - 3.35V
PP1V1_SLPS2R 1.1V
PP1V8_SLPS2R 1.8V
PP0V8_SLPS2R - 0.8V

--------------------------------------------------

PP2V5_NAND_SSD0 = 2.5V cycling

PP3V3_G3H_RTC_REG_R - 3.3V
PPBUS_G3H - 11.50V, not cycling.

On battery
All voltages above are still are cycling

PPBUS_G3H - 12.30V then 12.60V cycling.

So, I did the mistake of trying Revive.
It failed with the message.

Unexpected device state 'DFU' expected 'Recovery' (Probably forced into DFU mode externally)
[com.apple.mobileDevice.MobileRestore - 0xFAE (4014)]

After Revive failed it's getting 20V (0.400A increase slowly to 2A)

PPBUS_G3H - 12.10V on battery
PPBUS_G3H - 12.82V no battery and 20V 0.0720A on the charging port.

I replaced U7000 just in case of damage by the battery data cable. Still same.

Please, help.

 

[2informaticos]

Inspect for mechanical damage, sometime happens; knocked off components, broken trace.

Did you remove battery flex, before starting replacement process?

 

[ronaldo]

I think I left the flex cable plugged in. Just disconnected the battery.

 

[2informaticos]

Removing battery flex, disables the battery.
If you just remove the big screw, then battery may still make contact with MLB; if you don't lift the power connector from top of battery.
Battery flex alone can't send any voltage to MLB.

 

[ronaldo]

I use to place the black cover that goes on top the battery board between the battery Connector to isolate it.
Can the flex cable connected cause any damage?

 

[2informaticos]

Should not.

Did you try DFU with both charger and battery connected?
Force the machine off (hold power button 5s), then try to put in DFU with keyboard combination.
You may need restore, instead of revive; be aware, will erase the SSD.

 

[ronaldo]

I've checked the FPC screen connector J8500 and on pin 36 - I2C_ALS_SCL is shorted 5.3ohm diode mode 0.
The normal diode measurement on this pin is 0.463 according to another logic board.
This line goes to a 1.1K resistor R5316 pin 1 PP1V8_G3S and pin 2 receives the signal (I2C_ALS_SCL) from T2.

Do you think there is anything to do in this case?
Replacing the T2 from another donor Mac may fix the problem, but probably the data is gone.

 

[2informaticos]

Yeah, encryption data key is stored into T2.

If the short is present without LCD connected, then T2 is the first suspect.
Just in case, be sure is not caused by J8500.