When connected to your computer, can you see the reader directories in Windows Explorer?
Did you try a factory reset? I don't know how you do it on your model though, hopefully someone else will chime in or point you to a link for instructions. It will be something similar to the Glo though, which is:
1. Hold the power button ON for 15-20 seconds to make sure it is off. All lights at the top should be off.
2. Press and HOLD the light button while turning on the Glo. That should put you into a factory reset if that will solve the problem.
Maybe the Wiki will help you, further down the page there are instructions for a factory reset:
https://wiki.mobileread.com/wiki/Kobo_eReader
Factory resetting will lose all books on your reader though, so hopefully you have them backed up somewhere or all purchased from Kobo which should automatically download them all again once you set it up.