So I set my x0xb0x project aside to wait for a replacement q22 (to fix filter warble), but I went to check it again and now it makes no sound. Also, the middle row of LEDs don't light up (that is, the "black" keys on the keyboard).
- correct power into the main board,
- sound on the waveform switch, but only one note, which I can change with the tune knob.
- no sound on any of the pots.