How to make the drive visible under linux in upgrade mode

I managed to copy a file to it once with: sudo mount -t vfat /dev/sde /mnt/quad && {copy command}

I could ls and see the file, the drive unmounted, and I forgot to try mounting it again before switching off.

Now I can’t seem to get the file copied again, and when I ls, dmesg shows a bunch of:

[556630.715754] FAT: Directory bread(block 25) failed [556630.715772] FAT: Directory bread(block 26) failed [556630.715790] FAT: Directory bread(block 27) failed [556630.715808] FAT: Directory bread(block 28) failed [556630.715825] FAT: Directory bread(block 29) failed

I also notice that when I initially mount the drive I get something like:

johnny@picard:/mnt/quad$ sudo fdisk -l | grep 524288 -A8 Disk /dev/sdg doesn't contain a valid partition table Disk /dev/sdg: 0 MB, 524288 bytes 1 heads, 1 sectors/track, 1024 cylinders, total 1024 sectors Units = cylinders of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x2feff97d

But after trying to read and write I get:

johnny@picard:/mnt/quad$ sudo fdisk -l | grep 524288 -A8 Disk /dev/sdg doesn't contain a valid partition table Disk /dev/sdg: 0 MB, 524288 bytes 1 heads, 1 sectors/track, 1024 cylinders, total 1024 sectors Units = cylinders of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000

r/w operations seem to cause the disk identifier to change. Strange…