The cable connected to J9 on the M2-ATX needs to be connected to the motherboard on/off pin headers. You can see where these are on the MB if you look at the technical documentation.
For testing, we recommend using the P1 jumper setting in the M2-ATX manual for J10. This will give you a 5 second off delay, 1 minute AutoLatch setting, and 1 minute until hard-off setting.
J1 on the M2 needs to be connected to +12V. J4 needs to be connected to negative. J3 is the accessory wire. This needs to be connected to a switched +12V power source in your car. When this wire receives +12V, the computer will power on.