820-01598 boot issue

[Kyle93]

This arrived with liquid damage on U6903. Replaced U6903 and surrounding components. Goes to 20v 0.13a now.

PP2V5_NAND_SSD0 is 0v with an odd type of short. If the board is not powered on for a few minutes diode mode is .335 After power is applied and after checking about a minute later a short of 0.38 appears.

Removed all power filter caps and replaced u9080 but no change.

Anything else worth trying or is it a bad nand?

DFU mode fails with error 4025 "give up waiting for device to transition"

 

[2informaticos]

I suppose you've meant 0.038; as 0.38 is higher than 0.335.
This behavior may be caused by remanent voltage; even if you do not detect 2V5 there.
Can you catch another SSD voltage?
The G3S voltages come on?

 

[Kyle93]

pp3v3_g3s 3.3v

pp1v8g3s_ss 1.8v

 

[2informaticos]

I'm not sure if these DFU errors have any sense for Apple technicians even.
Pretty sure they will never release an explanation for such errors.

If basic voltages are present, not sure if something else than NAND and T2 can impede DFU completion.
Several times I saw that SSD voltages come on after DFU revive.

 

[Kyle93]

Must be a bad T2 then since that's the only thing that heats up on thermal cam.

Noticed a short on pp3v0_mesa. Replaced U4910. Short is gone. 3.3v appears on FL4910 but 0v on C4916