The built-in Windows formatter and some other formatting tools don't format exactly like a factory FAT32 format. Remove the SD card. Format the 255W correctly in FAT32 using RMUSBPrep: [Only registered and activated users can see links. ]. Your unit isn't bricked if you've only formatted it incorrectly, so you shouldn't need cure firmware. After the format, check it can be seen in Windows and then create a root folder named Garmin. Safely disconnect from PC, boot it and then connect to GarminExpress or WebUpdater & MapUpdater to replace missing files and maps. You'll have to manually add a [Only registered and activated users can see links. ].