What Kobo Touch Model do you have? Model number is on bottom edge of your Kobo.
Model N905, Model N905B or Model N905C
Model B and C have removable internal micro SD card. If you have Model B or C you can open your Kobo, remove internal SD card and install new image of your Kobo firmware.
These links might help.
https://www.mobileread.com/forums/sho...d.php?t=211265
http://blog.the-ebook-reader.com/201...readers-video/
http://www.partitionwizard.com/free-...n-manager.html