So nevermind about this:
Dear JYE team and community,
I successfully built the kit and calibrated C8.
However, I encountered an issue with the calibration of C5. No matter how I turned the dial, I can never get a correctly calibrated waveform.
In an attempt to solve my issue I tried to replace C4 with an unknown capacitor. As a result, the Test signal now doesn't work anymore.
Is there any way I could repair the test signal?
I'm kind of handy with electronics, but I'm not so good at finding out which component died.
I understand that it's quite difficult for someone else to figure out what got broken,
but you can ask me to do several measurements and I'll be happy to report back!
I'm actually not sure if it's really the Test signal which is broken, or the AIN.