View source for MacBook Pro A1706 Question mark folder or SSD not recognized repair

{{Repair Guide
|Device=MacBook Pro A1706
|Affects parts=Motherboard
|Needs equipment=multimeter, soldering iron, soldering station, thermal camera
|Type=Soldering
|Difficulty=3. Hard
}}
{{stub}}

==Problem description==
Question mark folder, no external boot possible & Recovery does not work on A1706 MacBook
[[File:Piccoloissue.jpg|thumb|Figure 1]]

==Symptoms==

*Question mark folder
*No external boot possible
*Recovery does not work

==Solution==

====Check R9350====

* Examine R9350 (PICCOLO_IUVD) on the board
** Check if R9350 is no longer soldered to the board. 
** Look for any missing pad for pin 1 (PPVIN_2V7NAND_LB). Refer to Fig 1 for visual guidance.
* Inspect the area near R9350
** Examine the trace coming out of Terminal 1 of R9350.
** Be cautious about the neighboring via, as it can break the trace.
* Measure the resistance of R9350
** Ensure it is within the specified range.
* Look out for potential trace issues
** Sometimes, the neighboring via can damage the trace, resulting in connectivity issues. Check for broken traces and continuity problems.
** [https://www.youtube.com/watch?v=m6lTkZnykqo Example of a broken trace] (Fixed by running a wire to replace the broken trace)
** [https://www.youtube.com/watch?v=WbuRSUitwCw Be aware of potential bad probe points, which may look good at a cursory investigation]

==== Check the Piccolo circuit ====
the Piccolo circuit can be sensitive to any sort of water damage in its vicinity.

* Probe inductors near the Piccolo chip. If they are shorted, replace the Piccolo chip. Injecting 1.3 V on these inductors usually won't give you a strong hotspot.
* In cases of no liquid damage, if the SSD is dead, It's probably unfixable.
* Measure C9416, Q9401, or U9400 for short circuit, it often happens due to issues with U9400 circuit
* In rare cases, there may be no damage in the R9350 area, but the TP above R9350 may lack PPVIN_2V7NAND_LB. Check the continuity between that TP and pin 43 (PPVIN_2V7NAND_LB) of J9600. In such cases, consider running a jumper wire from the closest source of PPBUS_GSH (pin 1 C6582) to the testpad after which, the SSD should now be detected. 
** After inspection and not finding any breaks in that PPVIN_2V7NAND_LB line, I deliberated on where to best access PPVIN_2V7NAND_LB from. I ran a jumper wire from pin 1 C9400 (PPVIN_2V7NAND_LB) and conformal coated that enameled jumper wire and considered it a viable repair.
* In other situations, a damaged trackpad cable can short PP3V3_S4_TPAD. This line goes through R5650 and then to R8901 as PP3V3_S4, and leaves as STORAGE_EN to go to J9600 lifeboat connector. It continues as STORAGE_LB_EN and goes to U9300 as its EN line. U9300 is the PMIC for SSD. Replacing the trackpad cable may resolve the issue.
* If the issue persists, and there was a history of liquid spill on the keyboard, disconnect the keyboard as it may be causing the problem.