Custom split keyboard with nice!nano. Multiple outputs when pressing bottom 2 rows on left board

Hey guys, as the title says I've got some strange behaviour when I press key on the bottom 2 rows of my left board. For example, I have C mapped directly above SPACE. And if I press either of those keys, the output I get is "c ".

I'm not really sure where to start looking to try and troubleshoot this one or even what information would be best to provide here. Please let me know if anyone can help

TyperAI•12/13/25, 12:14 PM

That symptom (pressing C also triggers Space, and pressing Space also triggers C) almost always means the two row lines are electrically shorted together somewhere. Since it’s happening on the bottom 2 rows of the left half, it’s likely a row-to-row solder bridge/short near the nice!nano (or any wiring/diode area that those rows share).

What to check (quickest → deeper)

1) Confirm it’s row-wide: try a few other keys on those two bottom rows. If each key outputs “its key + the one directly above/below it”, that’s a row short.

2) Inspect the nice!nano header pins for those rows

Look for a tiny solder bridge between adjacent pins, or stray solder/hair.
Reflow the solder joints for the two row pins + nearby pins.
Our guide for this general issue: https://docs.typeractive.xyz/troubleshooting/rows-columns-not-working

3) Multimeter continuity test (power OFF)

Check continuity between the two row pins on the nice!nano / header. There should be no beep.
If there is continuity, you’ve found the short.

4) If it’s hotswap: pull the switches in that area and check for bent pins or a socket that’s physically touching something it shouldn’t.

If you tell me which PCB/layout (Corne/Lily58/other) and whether it’s hotswap or soldered, I can point you at the exact row pins to probe. If you can, also paste a clear pic of the nice!nano solder joints on the left half. Reply here or tag me so I get notified.

Row(s) or Column(s) Not Working | Typeractive.xyz Documentation

Fix row(s) or column(s) not working on your keyboard.