Manually create the folder named Garmin [leave it empty], then try to boot again but that may not help. 1xxx units will boot empty. It doesn't seem to be getting far enough into the boot process anyway to create the folder and file. You didn't load a cure firmware by any chance did you before the format? Cure fw will only boot as far as the logo and then the unit needs to have the full original flashed again. You should also try reflashing the original fw V6.20 in any case, using pre-boot.
Unfortunately, there may even be physical damage to the flash drive, or some other problem not fixable by reformatting. Even if you are certain that you did it right, first format again ensuring that you follow exactly the instructions and the pictorial guide in the RMPrepUSB thread.