Vex EDR Clawbot Connection problem

Hi! I’m a student in a middle school TECH class experimenting with Vex EDR Clawbots. We are using the older version with manual setup. We are experiencing a connection problem with one of the clawbots.
We have tried resetting the cortex on the robot and the remote as well.
The robot works while it is tethered, meaning that when it is connected manually all the buttons work.
However, when we unplug the tether and insert the keys, all the lights turn red and it refuses to connect.
We have tried connecting with many different remotes and sets of keys, but no luck.
How can we find a solution to this problem?

Careful of how you tag your post. I found this in the IQ section when you probably should have put it in the EDR section.

As for Cortex troubleshooting, here is a troubleshooting flowchart for the status lights.