Last resort get image of internal micro SD card for Kobo Mini. Someone here can post a link for this image from their Kobo Mini. Write this image to new micro SD card that is 2 Gb or larger. Standard size of this image is 2Gb. If you write this image to Sd card larger than 2 GB expand the FAT32 formatted partition out to use the unused part of the Sd card. Leave the unused space at beginning of the SD card partitions. The internal SD card has 2 each ext2 partitions and one fat32 partition.
Remove the outer back cover with your thumb nail, guitar pick or corner of credit card. Starting at top right corner with front face down. Pull the cover off at top and around clockwise releasing retainer tabs from recesses. Remove inner back cover using Phillips tip jewelers screwdriver to remove tinny screws. Radio Shack has this screw driver. As you remove each screw stick it to adhesive tape strip or place in small dish to prevent loss. If you loose some of these screws drug store has glasses repair kit with 3 straight slot screws inside screwdriver handle that can be used. Radio Shack might have these screws.
Flash Drive Image Creator, Copies Image to your windows computer.
http://www.vconsole.com/client/?page=page&id=28
Flash Drive image Writer, Writes Image to SD card.
http://www.vconsole.com/client/?page=page&id=29
Keep your original SD card at least until this procedure is shown to work.
I use Parted Magic live SD to expand out the FAT32 partition. Gparted is available on Linux.