same thing for me. I also must have mismatched the gnd and signal line of the signal generator and fried it in the process. I actually can’t exactly retrace what I did but the signal generator seems gone. I have actually replaced the 74hc125 in the meantime and it didn’t help. I am not exactly sure what happend, I will have to have a closer look on the datasheet of the chip and the schematic of the dso nano but I guess it killed the output pin of the controller. I think I will do a blog post on that topic soon to share what I found out and also help seed to maybe improve the circuit. It’s really a shame … the DSO is not a bad product but I think there are some serious design issues. A simple protection diode for less then 0.05$ would be sufficient to protect the board and there is enough space left.