820-00163 2015 MacBook Pro 15" Restarting During Boot

[bjf]

I have a 2015 Retina 15" that turns on and starts to boot but shuts down and restarts at about 1/5 of the progress bar, just about 5 to 8 seconds after trying to boot. This board had some very, very minor liquid-damage. It had a blown backlight pin on the LCD connector. That has been replaced and the screen looks good. I'm not sure what's happening as verbose mode goes too fast to see. Hardware test came up with nothing. Any ideas?

 

[dukefawks]

Booted from external USB?

 

[bjf]

Attempted to boot from both internal SSD and external USB drive. Same result. It did boot however when I had no screen attached. I was in the system. Volume buttons worked. Shut it down with the keyboard shortcut. As soon as I hook up a screen OR an external display, it dies at that same point in the boot process.

 

[G.Beard]

May be EDID communication error so kexts are not loading... Possible
What happens if you boot into OS and hotplug an external monitor, do you get an image?
If so do you get QE/CI and correct resolutions?
What heppens if you boot in safe mode?

 

[bjf]

No Title

Ok, after testing it for a long period of time I've discovered that it will fail to boot in any state of display connection. And it will actually randomly (very, very rarely) boot in any state of display connection. I've seen it boot with the screen attached in normal and safe mode, and with an external display attached. It will also fail and restart in any of those states. Something is happening at boot to cause it to restart.

I filmed the boot process in super-slow motion and was able to capture this right before it crashes. This is the exact spot it stops every time.

 

[dukefawks]

It probably crashes when switching GPU. Does it boot ASD OS version? Try booting in safe mode to avoid kernel ext loading.
Also disconnect keyboard to rule that out.

 

[G.Beard]

The next verbose output you should see is "IO Graphics Flags".
When it does boot up and then crashes, does it throw a kernel panic?.... If so then there will be a log to look at which may help.

 

[bjf]

I do also believe it's something possibly with the switching, but not sure why the liquid-damage might have caused that or how to go about fixing it. As far as ASD, I don't believe one exists for this model so I'm not able to boot into it. It was a bottom spill and the keyboard types fine but I'll try disconnecting the keyboard tomorrow morning.

G.Beard- It's not displaying a panic, just looping in a restart. 1 in 30 times it will boot fine, whether in safe or regular mode. I did find one crash entry with com.apple.AmbientDisplayAgent. Not sure if that's what's happening every time, but it was in the logs.

 

[bjf]

No change with keyboard unplugged. Here's the one crash log I found. View attachment com.apple.AmbientDisplayAgent_2014-12-31-160039_Macs-MacBook-2.txt

Process: com.apple.AmbientDisplayAgent [194]
Path: /System/Library/PrivateFrameworks/AmbientDisplay.framework/Versions/A/XPCServices/com.apple.AmbientDisplayAgent.xpc/Contents/MacOS/com.apple.AmbientDisplayAgent
Identifier: com.apple.AmbientDisplayAgent
Version: 1.0 (1)
Code Type: X86-64 (Native)
Parent Process: launchd [1]
Responsible: com.apple.AmbientDisplayAgent [194]
User ID: 0

Date/Time: 2014-12-31 16:00:33.789 -0800
OS Version: Mac OS X 10.11.3 (15D21)
Report Version: 11
Anonymous UUID: 2C9B29D1-E130-E615-FC7E-4A8AE89008CD


Time Awake Since Boot: 10 seconds

System Integrity Protection: enabled

Crashed Thread: 5 Dispatch queue: DispEventQueue

Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0xffffffffffffffff
Exception Note: EXC_CORPSE_NOTIFY

VM Regions Near 0xffffffffffffffff:
--> shared memory 00007ffffff87000-00007ffffff88000 [ 4K] r-x/r-x SM=SHM

 

[dukefawks]

Only advice I can give is to put some flux and heat (NOT REFLOW) under the MUX and GPU, possibly VRAM if that doesn't work.

 

[G.Beard]

Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0xffffffffffffffff
Exception Note: EXC_CORPSE_NOTIFY

Means basically that it's trying to access data from a memory addess that don't hold the data it's looking for. No idea why that is happening.

AmbientDisplayAgent it would seem, deals with backlight brightness control and some other stuff based on the identification of the display plugged in being internal or external and what display type it is, and so on..... At least that is how it appears to me when looking at the text in /System/Library/PrivateFrameworks/AmbientDisplay.xpc//Contents/MacOS/com.apple.AmbientDisplayAgent.

Possibly confused about what is plugged in. Maybe DDC (mux / demux etc)?.... I don't know nearly enough yet.