In order to check and reseat the connectors at the Atlas motor you need to take off the left crank arm and the motor cover. Remove the left crank arm and the motor cover so you can access the plugs to the motor.
On the left crank (picture shows right- you only need to do the left side), loosen the 2 crank clamping bolts with a 5mm hex tool.
Remove the crank bolt (only on the left crank arm) with a 5mm hex tool. Now you can slide the crank off the spindle.
Remove the left side motor cover. There are 4 bolts and requires a torx t10 or t15 tool. Pull the cover off.
Now you can access the 4 plugs that connect to the motor. The picture below shows where these plugs will be.
The picture below is a close up of the ports on the motor. The plugs that fit into each respective port is color coded and different configurations so that they are not mixed up. You dont have to unplug these wires, but you want to wiggle them and push them in to ensure they are properly seated.
yellow port is power
black female port is speed sensor and tail light
blue male port is brake sensors
black male port is main harness