I had the same issue after cancelling the nav update warning. I downloaded the update from Genesis and just installed it. You need to ensure you have all of the files on the top level of your usb drive. It doesn’t work from the folder. Also needed a 128GB fresh drive because a 64 was too small. It took almost 1 hr but the warning stopped. Updated 5/24 @ 4:00 PM ET. Hope this helps for all.