820-00840 - Stuck on Apple logo - Progress Bar

[mccafe]

Hello guys!

I have a MacBook that had water damage. It had missing 20v which I fixed by replacing the type C chips and charging port. It had PPBUS_G3H, but no CPU core. Fixed it by replacing bad R7101 / C7101 and ran a wire to U7100 CPUVR_VIN. Now it boots, however it would never get past the Apple logo with progress bar. I notice that I never get GPU core at any point during the OS loading.

I was able to boot to linux with basic display drivers and so I imaged the SSD to back it up via dd command, but it seems like if I try to boot into the macOS, or installer it will just freeze up at a certain point. When I ran Apple diagnostics I would get the error VFD001 - "There may be an issue with the display."

What can be the issue? Could U7100 be partially bad? GPU MOSFETs? Anything else to check?

 

[2informaticos]

Disconnect internal LCD and test with external monitor.
Do not expect iGPU core voltage on boot; it appears only when high graphics load is detected.

 

[mccafe]

I disconnected the LCD and tested with external monitor with known good working type C to HDMI adaptor and it did not output anything. I also tested with LCD connected - same result.

 

[2informaticos]

USB mouse works?
Test it accessing boot menu.
If doesn't work, may need to change USB redriver; the chip which doesn't appear on schematic, nor boardview.

 

[mccafe]

USB mouse works fine when I boot to linux with user interface.

I replaced U7100 to rule it out since R7101 was blown right beside it.

I tried booting macOS with verbose text. These images are on two separate startup attempts. Output is a little different on each attempt, but maybe there is a pattern?

F740552-B-5-FDA-4-AA5-92-D6-EEBC1-AD5-B1-F6 hosted at ImgBB

Image F740552-B-5-FDA-4-AA5-92-D6-EEBC1-AD5-B1-F6 hosted in ImgBB

ibb.co

96-DEE33-E-BE15-4-F45-B6-FA-2104-D95723-DE hosted at ImgBB

Image 96-DEE33-E-BE15-4-F45-B6-FA-2104-D95723-DE hosted in ImgBB

ibb.co

 

[2informaticos]

Very likely bad CPU.

Remove internal SSD and try booting USB macOS.

 

[mccafe]

Thank you for your help!