Okay, the process is common around here, at least since we started to Chromebooks. We use a flash drive to "reinstall" the Chrome OS onto one and eventually, after "n" number of times, the flash drive no longer works. Since most of them were originally MS-DOS FAT flash drives I try to use a PC to reformat them but usually I can't and I take it to my MACPRO and run Disk Utility to format it as MS-DOS FAT and then verify and repair it (just for fun and to test it) and it kind of hangs at the end of the process saying "Updating Boot Support Partitions. . ." and I can quit Disk Utility and the drive seems okay but what would it be doing to a Boot Support Partition on a MSDOS FAT drive that wouldn't boot for lack of bootable OS?