I had this issue and the tech support guys suggested disconnecting the electrical line for each of the brakes in sequence. When I disconnected the left brake lever the bike worked perfectly. Support said that they would send me a new brake lever assembly. The bike is brand new...
Being a technical guy I thought about an what was going on and concluded that the lever adjustment screw under the lever must be out of adjustment. I backed off the screw 1 turn ccw and everything worked perfectly.  There is a magnetic limit switch in the lever assembly that activates when you pull the lever cutting off power to the motor. How could support not know this and why does the manual not have a caution note next to the paragraph about adjusting the brake lever position.  Better yet how does this bike ship from the factory with this condition present