Reference materials for assembling little keyboards.
Tools:
Once the PCB being worked on has been assembled with the controller and diodes, it can be tested for function. This is the best time to address an issue with the PCB.
Use tweezers to short the two holes in the switch footprint. Do this for each switch footprint on the PCB to determine if the keyboard sends a keypress when the tweezers are applied to the switch footprint.