Hello,
Asking for help motor 3 won’t spin (soldered correctly)
Setup: fettec fc, fettec esc, xnova 1804 3500kv
Thank you

Have you swapped motors to verify it's the motor and not the ESC?

It could be a bad connection on the FC-to-ESC wiring harness, so before swapping any motors try re-seating both connectors by unplugging and re-plugging them. And while they are out, use a magnifying glass to check inside the sockets for any bent or damaged pins.

I did my best checking the wiring connections and I didn't notice anything unusual, so I will probably proceed by checking if its a motor or esc issue

I switched the motors and it still didn't work so I tried a different esc, didn't work so I tried a different connector cable, didn't work so I tried running a separate wire from s3 on esc to s3 on fc, didn't seem to work either so what do I do now  heeelp meeeee gods of fpv, I just wanna fly

So if you've swapped the motor with another known good working one, and you've also swapped the ESC with a known good working one. and the ESC signal connection wire is fine then it can only be a fault with the motor output on the FC itself. Either a firmware mapping issue or a hardware issue. I'm afraid I'm not familiar with KISS hardware and software so I don't know it it's possible to accidentally unmap a motor output using the KISS configurator software.