Green leds on solid with usb attached

Everything looks good as far as preoperational checkout goes. Green leds light up when jogged, system is off. System powered up, blue led comes on and green stay off. Plug in usb cable to computer and green leds on solid. Sounds like z motor hums.
What’s happening?

When you plug in USB the gShield locks up the stepper moters so that they don’t move. It does this by sending current. Is this what you are seeing?

So that’s supposed to happen. I must have missed that part in the readings. I just wanted to make sure I wasn’t going to smoke something