Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Is this actually a trunk or a liftgate/tailgate?
Are you trying to open it with a button from the inside of the vehicle a remote key fob or using the key?
Have you checked the fuse/s?
I would either have the codes retrieved from the body control module to help diagnose this problem or for now just try a new liftgate relay.
If your mechanic wants to further troubleshoot why the liftgate won't work, here is a troubleshooting guide