According to Haynes, Fuse 2 in the battery junction box (30 amp) powers the liftgate glass actuator. The actuator is signaled by a relay either from the rear tailgate pushbutton or from the security system via the key fob. The security system will only allow the pushbutton to work if the security is deactivated (unlocked).
So, the problem could be the fuse or it could be a faulty Liftgate Glass Release Relay. The relay is mounted within the Central Security Module. If memory serves me, that is located under the rear passenger interior trim panel.
Have you checked whether the key fob is working to release the glass? That will rule out the fuse and the relay and leave only the rear switch and wiring.