deleting slot 1 will stop your box booting if you haven't changed the boot order as this is the primary/default slot, to get it to boot up you need to do as pablo says above. Your USB is not being read by the box, to correct this fully low-level-format the USB with a formatting tool such as HDDGURU & then give the USB a FAT32 format before you load flash files (often a FAT32 format isnt enough to prep the USB correctly). IF you have any further issues flashing the box buy a NEW 4gb - 8gb USB pen drive, FAT32 format it to prep before loading flash files.