I personally like to investigate such issues. But you did pay for a working product so to each his own but it could be simple.
first I’d check all the open gears to make sure nothing is in them. Also check for any idler gears or main axles that have slid past the idler and thus locked up the truck. If nothing is immediately obvious then it’s time for a closer look. Turn the truck 90 degrees and it will come loose. Be sure NOT to lose the LionDrive coupling that will be between the truck and motor. From there you can check that the motor spins. I’m not sure on that AC6000 but sometimes there’s a little PCB on the top of the truck where you can unplug the electro-coupler and be able to deal with the truck completely separately.
