Button matrix reverse engineering

[joejoebinks693]

Can someone link a guide or video to reverse engineering a button matrix? It's for a label maker I fully understand how button matrixes work but I'm having trouble reverse engineering it 

[bowrilla]

What exactly do you want to reverse engineer? If you know how a button matrix works just follow the traces on the PCB and identify which way any diode is orientated. What else do you want to reverse engineer? Anything else will require you to probe the board.