2020 MacBook Pro M1 bootlooping after repair.

[Gueric]

Basically, this never opened before MacBook Pro had some liquid damage around a few keyboard backlight components, that I replaced. Turns out it wasn’t the actual issue, the actual issue was a defective CD3217.

Removed it, replaced it. Laptop booted fine, I erased it, installed a new macOS version, checked battery health, speakers, screen etc. Turned it off to put everything back together, turned it on again, and it started bootlooping.

Chime, shows apple logo, then a progress bar, and when it fills at about 1%, reboots. Back to the Apple logo, progess bar almost empty, reboots a 3rd time, then shows an exclamation mark with the /restore link, and the fan at full speed.

When shown this exclamation mark, long pressing to shut down the Mac makes it pulls 1.5A, possibly charging the battery.

I don’t know what to look for as I’m very confused.
both CD3217s pull 20v and behave the same. Probed a few SSD lines (2v5, 0,8v, 1,25v) and they’re not shorted.

The bare board also bootloops. Interestingly, when plugged into my Mac (so, 5v) the board alone pulls a little bit of current, reboots, then stays at 5v 0A. No bootloops.

thank you very much in advance.
If you are mon2, then hey mon2.

[mon2]

LOL. Hey. I have no life and a few minutes before my Netflix binge watching.

Check your trackpad cable. There are sensors in the trackpad and fan at full speed is often linked to the trackpad. Be sure the contacts on the flex cables are clean. Do inspect them for debris, etc.

[Gueric]

Hey mon2 I'm not gonna complain if it allows me to fix my stuff and learn lol.

I checked for everything, and I have a few interesting things to add.

It is rebooting 3 times, then shows a restore exclamation mark, and from this point stays on the restore screen and never boot loops again and pulls way more current (1.5A when plugged into the wall, and 2.5A when plugged into my other Mac at 5V) CPU is cold, NANDs too. I don't think the issue is with the CD3217s. Also, when at 20v it pulls very little current during the boot loop thing.

Also, fan is not spinning at all anymore, and the trackpad does indeed click on the restore screen.

[Gueric]

Small update. I tried to reflow both of them, and its even worse now. I believe one or both (the one i replaced and tje one i didnt replace) were defective from the start. It’s now pulling 5v, a bit more current at 100-280mA, and bootloops way faster and more. I ordered a dead M1 and ill update when both CD32s have been replaced.

Good binge watch to you :p

[mon2]

Review the ldo rails of each pd controller.

[Gueric]

so, mon2 I just checked almost EVERY single pin of BOTH CD32s using diode mode. everything looks fine.

I just realized that now only the CD3217 I didn't replaced negotiates 20V. the other, that I replaced and that worked for a few hours, negotiates 5V at 0A, and doesn't make the board boot loop. So I guess it's defective because the reball was good and I even tried a reflow.

Let me know what you think