Have you tried manually flashing new firmware?
https://pgaskin.net/KoboStuff/kobofirmware.html I used glo firmware 4.38.21908 on mine put it into the .kobo directory when your hooked to a computer. It was fussy for me after factory reset and took several tries. If your original firmware was old and you didn't do the mandatory update you might try 4.34.20097 flash it and then the newer one. Its working but my wifi isn't I have a post but I imagine my problem is my router not the firmware.