Donald,
a schematic is not sufficient. A detailed and accurate wiring diagram, or, better yet, a photo of the wiring is required. A schematic is a 'logical' view, how it's really wired is what is important.
Then Connect the PWR of the battery to VIN of Moteino, it still does not work. When I added a 12v-to-5V step down inbetween the PWR of battery and VIN of Moteino, it worked.
What kind of 'step down'? Maybe you have high voltage spikes on your 12V PWR at the motor board. If that is the case, perhaps this connection will work:
1. Connect Battery to Motor Board PWR & ground.
2. Connect Moteinto Ground to Motor Board ground but at a Signal input pin, not a PWR input pin.
3. Connect Battery + to Moteino Vin.
Of course, if the Step Down ALREADY works, can you use this?
Can you post a link to detalis about your motor board? (schematic or manual, mfr & model, etc)
Tom