A few more things to check. Pull out your multimeter
1. What is the battery voltage at the lug nuts on the power distribution board?
2. What is the voltage the cRio power plug is getting (the "V" and "C" pins)? Is this wired the correct way (with +24V to the "V" and gnd to the "C")
3. What is the voltage the digital side car is getting from the Wago connector? Is this plugged in the correct way (with the + and - printed on the side car)?
4. Does the classmate PC show that it's connected to the cRio?
5. Is the stop button plugged into the classmate? Has it been pressed?
6. Is the robot enabled on the classmate PC?
7. Is the 37-pin DB extension cable between the cRio and the side car firmly seated on both ends. Have you tried a different cable?
8. How are the dip switched set on the cRio?
Also, pictures say 1000 words... taking some pictures of how things are wired (specifically the cRio and digital side car) could really help. A picture of the classmate PC dashboard could also help. Take all the pictures with everything on and enabled.