2021 TLX Type S
It can take much more than an hour to finish. If you turn the car off you interrupt it. So, you must leave the USB plugged in, light blinking (this is much easier if you have a USB drive with a read light), in accessory mode, go in and have dinner, and wait until it is finished. It may take a while, like up to two hours. Mine had a banner that said it was finished, but based on other comments you may have to wait until the USB stops flashing for a while (it will periodically stop flashing for up to 30 seconds then start flashing again). It is a 15 GB file, and it takes a while. Also, to restart, be sure you press the START switch until everything is off (do not put your foot on the brake or you will start the engine), and then OPEN THE DOOR. Remove the USB drive. Only when you open the drivers door does it actually turn everything off (this is there for a good reason, while you wait on a passenger to finish shopping while you sit in the car, it keeps everything on in accessory mode). Turn the car back on into accessory (don't press the brake put push the START switch once), then by going to the navigation menus, then help, you should see the new file date appear).