Question 2 hours of sanding but 1V is still shorted

[porc]

First timer here. I'm working on a Wii-in-GameCube project based on Nold's Miicro and I just trimmed my 6-layer board but even after 2+ hours of sanding my 1V is still shorted to ground. I'm hoping someone can help me troubleshoot this and figure out how to find and fix the short. All other voltage resistances look good other than 1V. I have a couple theories: I cut through the USB and memory card solder points which both still have some solder in them, maybe that could be it? I'm relocating the USB and not using the memory cards so I didn't think anything of it. Also, I slightly nicked the board in one spot near the U5 and there's exposed copper, could that be an issue? If it's not those things, maybe I just need to keep sanding, but I've gone all the way to 1200 grit all the way around and I can see the layers all the way around so I feel like that's not it. But again, this is my first time so I really have no idea. Any advice is appreciated! I've attached pics as well. Thanks in advance!

 

[porc]

also ignore the terrible U10 relocation - it's ugly but it works lol

 

[Stitches]

When you say it's shorted, is the resistance value 0-1 or is your multimeter just beeping? Multimeters tend to beep at resistances below 50ohms, which for some voltage lines is normal

 

[porc]

The resistance is at around 4-5 Ohms

 

[porc]

You know what, I'm reading the Wii Trim Resistances thread and it looks like that might be normal for a 6-layer. I was seeing all the 4-layers having resistances higher, in the 30+ Ohm range, but looking at the two 6-layer posts there my resistances are actually almost identical. I think I might just be an idiot

 

[porc]

This is what I'm getting, does this look right? the GND-1V is the only one I'm worried about

 

[Stitches]

I'm not too familiar with the exact expected 6 layer resistance graph, but since we're talking about 1v to ground, you can just wire it up and see if the board boots. If there is a short to ground, you won't damage anything by doing a power on test. It's mainly the voltages shorting into each other that's a death risk, and the resistances between your voltages look fine

 

[porc]

Ah, ok great, that is what I was really worried about. Makes sense. Thanks!

 

[Stitches]

Ah, ok great, that is what I was really worried about. Makes sense. Thanks!

Actually it would probably save some time to just wire 1v (plus a ground wire of course) to the trim and check the voltage with your multimeter. If it doesn't tank below 0.8v, you're good to disconnect the power and wire in the other voltages. If the voltage does plummet to almost nothing, then there is in fact a short and we can try to find it

 

[porc]

Just tested and we're sitting pretty at 0.99 volts

 

[Stitches]

Excellent! You're good to disconnect the power and wire the other voltages now. Remember to use 2 ground wires since it's a 6 layer and 1 ground wire is usually not enough