Good stuff. All I’d say is either check at the nearest neighbour corresponding to the resistor in question,if nones availiable just scratch back the trace/s slightly before. What can often happen is you probe the suspected bad resistor and if the endcaps are bad, probing it directly can make it “good” again unbeknownst to you - I’ve chased my tail in situations like this all too often. Filters at P13 are also notorious for this too.
Good point, the probe could push the endcap back into making contact temporarily I’d imagine
Also the soc reball by hand took about 3 hours with a few breaks to rest my wrist
Now I feel like going over the whole board again in case I missed something, after I sort out a different switch in front of me that is, don’t suppose anyone came across a switch that won’t wake up after being put into sleep mode?
thanks for this, I put one on order myself as i’ve been meaning to learn how to dig deeper into this stuff.
Exactly 
Ouch, yeah not surprised about the wrist.
Not off the top of my head sorry.
Some images of the board;
imgur dot com/a/Q72VN6y
I’ll grab some close ups with my microscope later on
Excuse the various solder blobs on the board, I was monitoring different power rails for info etc
Not sure if there is anything left to check or rule out with this board other than the soc, also not sure if I should expect voltage on both sides of every resistor on the board, yes I went and checked each ones voltage reading
Sorry not sure if it’s imgur having maybe compressed or cropped these images but I can’t do much with them as it it’s a blur to begin with and then vaseline when zoomed in 
Nah. Some resistors are pullups, so you’d see a voltage on both sides (depending) and some are pulldowns (one side connected to ground) so you’d always measure zero one end on those, some will be for enables and the like and may not be active until some other step. So yeah don’t bother next time unless you know what your measuring 
You’re right the images I uploaded look like they shrunk, they should have been something like 4x that size, i will upload them again or try to take some in better light
As for the resistors, I figured that would be the case and without a working board to check them against it didn’t help me find anything out of place.
I’ll have to pick SheriffBuck’s brain on how to use a usb data analyser, how to set one up etc, not that I have one yet, will be my next step and something new to learn
of course my last resort will be an soc reball before calling the board not fixable
made sure they were the proper size now, imgur dot com/a/WdF49y4
Sorry man it’s all still a bit too fuzzy and out of focus for me to truly get a good idea what’s going on. If you can, can you take them using natural light maybe? that might produce better results. If I cant read the chip markings and clearly see each individual pin then that would be your indicator that I won’t be able to see what’s going on. Given the distortion are you taking these pics with your camera through the eyepieces or something?
Can you explain what looks like the repairs you’ve done at the main PMIC and fuel gauge (if the fuel gauge has been repaired… hard to tell from the photo) just so I have a better idea.
IC to the right of the PMIC with what looks like residue around it, again bit hard to tell from the photos, is this flux/IPA residue or? possibly at the crystal near the custom asic too (but hard to tell)
I notice a lot of caps bridged end to end, I’m pretty sure most if not all will be connected to the same corresponding line/s but you might want to resolve all this and neaten everything up just incase one isn’t supposed to be, that and because it’ll look nicer .
Also this is more personal preference but I’ve gotta be honest (please don’t take offense) I hate it when people solder their ground leads to screw hole pads or connectors… I just don’t see any good reason for doing this, for a start it’s not a great source for ground on top of the USB (it’s tin/nickel plate steel) and if using the screw hole pads, even if they’re wicked afterwards (which is rarely done on the boards I look at) solder is still inevitably left behind and as a result of the screws going in I often find solder flakes all over the place or if they didn’t wick it I often find the corresponding thread on the frame is stripped and/or the board is now going to sit slightly prouder in the chassis in these spots - just solder to the through hole pads on the back of the USB which are meant to take solder, problem solved or find a TP which is ground or ground side of a cap or something.
Sorry if I’m asking you questions you’ve already answered, this threads gotten pretty long
I’m taking them with a nikon digital camera, i’ll try different modes and lighting, this camera isn’t great for close-ups
What you see near the PMIC is the left over piece of a wire I used to monitor that rail while the switch was in the case, i had solder mask on it and to keep it from moving and didn’t remove it yet
I replaced the max 77620A due to a missing rail so there is some IPA residue in the area, the whole board needs a good cleaning eventually
I replaced the fuel gauge as well ages ago so there is some IPA residue in the area
I’ll go ahead and tidy up the bridged caps (all bridged on ground side) it was from going over the caps etc when I thought there was a simple connection issue
Lastly I’ll start using a better location for my ground leads 
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Thanks to SheriffBuck I was able to verify that the gpu buck enables and outputs 0.95v
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Cleaned up and took far better pictures,
imgur dot com/a/tu9h6dG
Also I can’t seem to remove that test wire piece that I soldered to the test pads then put solder mask (near max 77620), it got hard and I don’t want to force it, so I will take care of it if the board ends up as a working board
Nothings really standing out to me other than your GPU buck is a skew (I’m guessing you over-exposed the solder mask when wicking here?) given you mentioned it’s producing it’s output then it’s probably fine but I’d pull it and fix the mask if it were me. Chip in the fet (maybe) above M92 - again, probably fine. Though all still a bit hard to tell, the pics are way better but because of the artificial direct lighting I’m still struggling to see because of the shadows.
Anyway besides the above, I think given everything, your at the point of reballing the SoC/Ram at this stage in the game. I’d probably take the board out of the equation and transfer the SoC (and EMMC) over to another PCB which died of unrelated issues. that way if it doesn’t work you can say the board was fine and then don’t have to deal with reballing ram too
I’ll swap out that fet, there is a small chip in the corner that I never noticed
When I replaced the gpu buck, I may have forgotten to give it a very slight nudge when placing it, pretty sure I didn’t damage any solder mask, the issue may be from me trying to limit how hot the hot air I used in this area was due to the plastic connectors even though I protected them.
If I nudge the gpu buck and it straightens out, think it still should be removed and have the solder mask checked?
The light in the images is from my window on a sunny day since I don’t have a good desk light
I only have one other switch board currently, the one that has a dead nand (my other post) I guess it would be a good candidate for the swap, guess there is too much of a risk to the soc to reball it and put it back on the current board first before swapping boards?
thanks for the replies
You shouldn’t have to give any IC a nudge provided your up to temp and everything was properly prepped
Yeah that could well be the reason
If it were me I’d want to check it. If your hands are really steady you can lift the IC straight up, inspect the joints and mask, if all checks out then plant the IC backdown and reflow. This is tricky though and requires practice… might be safer to just reball from the off
Oh, my bad… usually when you get reflections and shadows like were seeing it’s usually because of down lighting and the sensor not knowing what to do
Yeah that would be a good candidate.
Yeah, primarily it’s SoC health but also it might be board issues on your currennt PCB is at fault, you might reball, it might not work and youd call it all bad atleast this way you can start ruling stuff out. for example if it doesn’t work on the other board also then you know you’ve likely got another “known” good board for a future transplant
The chipped mosfet and gpu buck correction made no difference.
So I pulled the SoC, I don’t see any pad damage or oxidation etc, I’ll probably finish the process(reball) tomorrow then update here
By preheating the board the SoC came off from both boards in under a minute, went smoothly thankfully
Well after swapping the soc to another board I get the exact same issue, so I can say with certainty that the SoC is dead.
I definitely learnt my moneys worth out of this particular switch at least
Thank you @Severence and @SheriffBuck for the assistance on this one
(For those who stumble upon this topic with a similar issue)
With the official charger;
0.07a draw with no nand module
0.08a draw with the nand module
0.22a draw with 5v usb pc connection
Can accept and display payloads
Black screen when booting normally, no backlight
Black screen and no backlight when booting into original firmware from hekate
Freezes on the atmosphere logo when booting into custom firmware from hekate
Freezes on l4t logo when booting the linux for switch
SoC warms up as expected
SoC makes the chirping sound (confirmed on a working switch)
Sorry to hear that at least you narrowed everything down and positively identified the SoC as the culprit I suppose you now know you’ve got a couple of working donor “transplant” boards (though I’d be somehwat weary of you patient board in this case)
I think the most interesting part for me which needs clarifying or that I need to verify myself is the [secondary] CPU rail coming up so soon… this may or may not be a good indicator (of course outside of the regulator itself being at fault) or it’s entirely possible I’m remembering wrong about it’s normal behaviour