Macbook Pro A1989 820-00850-A not turning on.

joshAU

Member
Hi all.
We replaced a display assembly with an aftermarket screen.
The customer bought it back a few weeks later stating that the hinges are too tight.
I checked the system booted, and confirmed the faulty hinges, then shut it down, and removed the assembly and replaced with another aftermarket screen.

It failed to turn on, or display anything on either the internal or external monitor.
I then retried with the original screen but the result was the same.
I usually remove the battery cable and undo the battery screw to isolate the battery while disconnecting and connecting the screen, however, it is possible that I overlooked doing that this time.

Using a 96 watt Apple AC adapter.
20v on all 4 USBC ports, in both orientations.
No USB LED activity on a known good USB memory stick, in any port.
No capslock light.
No fan.
No chime.

PPBUS_G3H = 12.64v
PPVIN_G3H_P3V3G3HRTC =12.45v
PPVIN_G3H_P3V3G3H = 12.64v
3v3_G3H_RTC = 3.39v
PP3V3_G3H_RTC = 3.39v
PP5V_G3S = 5.17v

Should I try a DFU restore?

I'm a bit rusty on Macbooks lately.
Any help or suggestions greatly appreciated.
 

joshAU

Member
Hello once again 2informaticos, and thanks for your help.
Yes, I disconnected the screen, and tried it on the original screen that was working, but had stiff hinges.
No display on either, nor on a external screen.

I am able to get it into DFU mode, however, when I try Advanced-Revive Device, it gets to the stage "installing"
then fails with the following error:
"The system cannot be restored on this device"
"Unexpected device state 'Recovery' expected 'RestoreOS' Probably caused by"...etc....
then finally com.apple.MobileDevice.MobileRestore-0xFAD(4013)
I've tried with another USBC cable..
As the customer does not have a backup of their files, I do not want to try the "Erase all contents and settings" option.

I tried to put it into DFU mode again, but now it just comes up as "recovery" instead of "DFU" in the Apple configurator.
.
 

joshAU

Member
Sorry for the delay 2informaticos - I'm only working a few days a week at the moment.

While I have the unit connected to my work mac, which is running the Apple Configurator, and is displaying "Recovery", I measured the coils.
L6900 reads 3.38 Volts
L6901 reads 3.38 Volts
L7030 reads 4.23 Volts
L7600 reads 5.16 Volts
L7660 reads 3.38 Volts
L9021 reads 0.90 Volts
L9020 reads 0.91 Volts
L9030 reads 1.80 Volts

All other coils read 0 Volts.

I also got a voltage on L9080 and L9081, however, when I was checking, I realised that something was getting incredibly hot near by.
I am guessing U9080 was the one getting hot.
I removed USBC power, and disconnected the battery, and let it cool down.
It appeared that the 4 capacitors right nearby, C9088, C9090, C9092 & C9089, all appeared to be directly shorted, i.e. 0.00V.

Now however, it doesn't get hot.
I no longer get 20v on the USBC ports, only 5v,
I no longer get any volts on any coil.
All coils on the board now read 0 Volts.
The unit no longer shows up in Apple configurator at all.

I'd say things have gone down hill rapidly on this one. :(
 
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