Macbook 820-00165 will not fully boot

[Instafixx]

Hello,
Namaste.

I have a Macbook A1466 820-00165. The machine boots up. Chimes. Apple Logo.
Progress Bar.

It comes to the login screen and then after 3 seconds it turns off.

If i press the on/off key it ll again turn on and then turn off the same way.

No corrosion on the board.

Tried removing the SSD and booting. Same issue. The question mark folder will appear and it ll turn off.

After it turns off i still have a stable PPBUS_G3H and PP3V42 etc.


What can be the issue?

[mon2]

Re: Macbook 820-00165 will not fully boot

https://www.it-tech.com.au/how-to-re...halfway-issue/

[Instafixx]

Re: Macbook 820-00165 will not fully boot

https://www.it-tech.com.au/how-to-re...halfway-issue/

Let me check this out. But my machine doesnt even boot into the Apple Diagnostics Mode. It ll switch off half way.

[Instafixx]

Re: Macbook 820-00165 will not fully boot

https://www.it-tech.com.au/how-to-re...halfway-issue/

The parameters don't suggest a failed Q1920.
When the fan is on i am getting power supply of Q1920
PP PP5V_S0 1V5_S0SW_AUDIO_HDA and PP5V_S0

But when fan goes off these rails are 0V.

[ACS-Repair]

Re: Macbook 820-00165 will not fully boot

I've had a couple of these 820-00165 that would either kernel panic at startup or crash every 10 minutes after starting up. I have not been able to solve the one with the kernel panic but I found some components broken off the board on the latter.
Specifically, I found R2281 was not present and after restoring it, the computer no longer crashes. If the board has always been in the computer it may not be likely that components are missing, but if you don't know the history of the board it's always a good idea to scan for missing parts.

[Instafixx]

Re: Macbook 820-00165 will not fully boot

I've had a couple of these 820-00165 that would either kernel panic at startup or crash every 10 minutes after starting up. I have not been able to solve the one with the kernel panic but I found some components broken off the board on the latter.
Specifically, I found R2281 was not present and after restoring it, the computer no longer crashes. If the board has always been in the computer it may not be likely that components are missing, but if you don't know the history of the board it's always a good idea to scan for missing parts.

I found no component missing as such. But while cleaning the board 2 caps fell out. Put those back in place. Thats it. The board has no history it seems . I am totally stuck here

[mon2]

Re: Macbook 820-00165 will not fully boot

Try booting with a SMC BYPASS.

[Instafixx]

Re: Macbook 820-00165 will not fully boot

Try booting with a SMC BYPASS.

It is not happening.

Tried SMC Bypass.
Tried Safe Mode.

Its still the same.

It boot up.
Login screen appears.
Fans becomes fast and it goes off.

[Instafixx]

Re: Macbook 820-00165 will not fully boot

Try booting with a SMC BYPASS.

One of the components that fell off was R5117 which is the CPU_THRMTRIP_3V3 line resistor.
Not an expert but the name suggests that it is thermal monitor of the cpu and will trip the cpu when too hot?
Is that the case with my Macbook as the fan becomes fast before switching off as if the machine becomes too hot.

When the fan is spinning and the machine is booting up
CPU_THRMTRIP_L is at 0.02V.

When the fan stops and the machine is off

CPU_THRMTRIP_L jumps to 3.3V.

[UPDATE]

Removed the Heat Sink and found that the CPU is indeed getting really hot when the Machine Starts.