Didn't fix my wife's Kobo won't update but after I got the "NEW zip file"applied I made an image of a blank user then reinstalled all her apps contacts etc. Then made an image of that. I have used the Gdiskdump to make the images and reinstall them back to the internal card. One gives me a blank running March 02 system and the other gives me my wife's fully operational system. Won't get stuck with a dead tablet and unhappy wife again
It took a week to get this running again. Had to install an relearn Ubuntu Linux (installed by Kubuntu by mistake and had to switch desktops to get Gdiskdump installed and working.
When I installed your Kobo image it still did the install update stall at 40%.
So when I did my blank image I used a false Hotmail address and false Kobo account. It should get to an operating system that asks to update, which one could ignore!!!!
Linux seems to be the best way to handle Android.