I had a virtually identical situation, save my Kobo Mini was stuck on the load screen but could be turned on and off.
Thanks to this thread, I - as a computer literate person but not a coder - was able to fix it.
Here's how:
1. I downloaded the Kobo_Mini.img and unzipped it, as linked
here
2. I used an 8GB micro SD card (as that's all the local shop had)
3. I found Win32 Disk Imager from
here and installed it to my elderly PC running XP Pro
4. I opened the unzipped image file in Win32 Disk Imager and saved it to the micro SD card plugged into drive E: NOTE: it takes about 20 minutes to copy.
5. I put the new micro SD card back into the Kobo Mini and switched it on, then did a soft reset when nothing happened. The setup screen appeared and I am so happy.
Thank you to everyone who made this possible: you empowered me to fix it myself. I don't have the money to buy a new Kobo and it was just 6 weeks past the guarantee's expiry. I paid £8 for a new micro SD card, not £80 for a new device.