A2337 boot-looping

[Soji]

History
The owner change the screen and the apple boot loop started.
It’s not entering dfu or recovery
I think it’s a power problem
The usb-c ammeter too restarts every time apple logo loops.I think It’s like a voltage or current loop.
Pls what to do next.

 

[2informaticos]

Disconnect internal LCD and test with external monitor.

 

[Soji]

Just tested it with external monitors, no display on external monitor. It still loops and the typec ammeter restart every time it loops

 

[2informaticos]

Very likely the owner worked on the machine without disconnecting the battery.

Machine restarts w/ and w/o battery too?
Try starting in SMC bypass mode.

 

[Soji]

It’s still recycling with and without battery
Smc bypass to is not going through. When it reached that time it bootloops , no matter the task it will turn off

am thinking it’s a power thing, the power recycles

there is a big coil next to speaker
connector 2r7 written on it. The 12.3 sometimes 13.2V goes to 00.00V when it loops
I don’t have the schematic yet. Pls can you give a link to buy.

 

[Soji]

It’s a MacBook Air M1 chip. It’s still a recent laptop. So I don’t really get what you said,

you mean I should replace the nand chips.
and how do I do the second boot device( boot from a flash ?)

 

[2informaticos]

L5230 is not the point where to check PPBUS_G3H.
Check at F5200, w/ and w/o battery battery connected.
If is not stable, you must check for short on all big coils.

02016 X1757 Rev_4.0.0_.pdf

drive.google.com

 

[2informaticos]

You can't do anything until get stable PPBUS_G3H.
And this fluctuation is not LCD related; as can be checked without LCD too.

 

[Soji]

Thanks for the schematics.pls what can I do to get ppbus stable.

 

[2informaticos]

Check for knocked of components, broken traces.
The problem was induced by owner; when changed the LCD assembly.
Something changes if try disconnecting internal LCD?