Removed the MIDI board, and now my Core is not working

[Agoraphobe]

As the title suggests, I just had this happen to me.

The Core worked as intended, I cut the board and soldered a pin header to it, as well as soldering GND, VDD and PC0 to a pot to patch it up in the software.

When I connect it to my PC via the same micro USB I've used before (which still works for charging and transfering data from my phone) I get no LED lights and the error message "No available USB device found matching PID/VID". When I try to use rescue mode (DFU) I get the error message "No device in DFU mode detected", which suggests it's a hardware issue. Did I cut the board wrong? Attaching a picture to this post.

EDIT: I just tried removing all connected dupont cables from the pin header, so I'm only left with the board (minus the MIDI section) and the micro USB. I still get the same message.

Any help would be much appreciated!

[Agoraphobe]

Oh no....

Upon closer inspection of the board I saw this:

How does this happen? I've only ever used my computer's USB to power this thing. One of the capacitors was completely fried and just fell apart when I touched it. Faulty board? I sent @johannes a PM. Fingers crossed!

[SmashedTransistors]

Maybe it is a similar issue as this one:

Defect after cutting corners

The board is a four layer board - the two internal layers are used for power. They are very close together and tiny copper splices from the cutting can easily short them out. You can try to find shorts on the supply rails with a multimeter - I highly suspect that's the issue you're having there. If not - then I don't know. If you find a short between the supply rails: You can of course try to fix it with very fine grid sandpaper (Sandpaper with grid no. 1000 or similar). You might be able to s…

[Agoraphobe]

Yeh, maybe, but I didn't touch those corners, only removed the MIDI part following the "perforated" line

[spacelordmother]

OUCH - Got fried good.

[SmashedTransistors]

Even so, if you did not use sandpaper to remove tiny copper splices were you sawed, maybe you short circuited the internal layers...

[Agoraphobe]

Is there a better/faster way of contacting johannes than DMing him here?

[lokki]

The Core worked as intended, I cut the board and soldered a pin header to it, as well as soldering GND, VDD and PC0 to a pot to patch it up in the software.

your "timeline" is not very clear here. i assume the board was working correctly and then you did all of the operations (removing midi board, soldering pin headers) before trying again? if so, the issue could also be with the soldering of the pin-headers maybe? can we see a picture of the back of the axoloti with the solder points? as hi-res as possible.

[Agoraphobe]

Your assumption is correct. I'm about to move to a new house and all of my electronic stuff has been packed down in boxes. I've soldered for many years so I really doubt it could be the culprit, unless you have something specific in mind. All points have enough solder and none of them are touching each other. @lokki

[lokki]

unless you have something specific in mind

i don't want to question your ability to solder, but i have seen cases where some excess solder shorted the pcb layers. if i remember correctly there is a 3.3v and a GND plate incorporated in the 3 layers of the pcb. so if you have any solder on the thin back of the axoloti, remove that and also try to file it as others suggested.

[Agoraphobe]

Thanks for the suggestion @lokki, but that one cap is already fried to ashes. I'll have a look once I've settled in at the new place. Still waiting for a reply from johannes.