[ischmitz]

One quick tip for bench-testing. The two pins where the brown wires are connected to are interchangeable. To test the box remove it from the car and test with an Ohm meter that there is 0 - 2 Ohm between the two pins and each pin to the chassis of the box. If any of that doesn't check out you found your issue.

Then get a couple of wires and connect +12V to where the red lead goes. And the GND lead can go to either of the pins where the brown wires go or even to the outside chassis of the box. It needs to make a noise.

A non-humming CDI is either a failed internal connection of on of the the GND leads or a damaged PCB due to overvoltage in 99% of the cases. If the PCB is damaged it often has taken out other components internally that need to be replaced.